D&D 5e has actions, bonus actions, and reactions. People frequently also use the term move action when talking about the kinds of actions you can take during your turn.
However, a “move action” isn't a kind of action in D&D 5e. This misconception seems to have come from carrying forward experience from D&D 3.xe and 4e, which do have move actions.
How can it be best explained and cited that there's no such thing as a move action in D&D 5e, when someone makes this common and understandable error?
According to the PHB, page 189:
Your Turn
On your turn, you can move a distance up to your speed and take one action.
This means moving is not the same as taking an action. You may always move a distance up to your speed on your turn without taking any actions (barring special conditions — but let's not get into that!).
That you can always move on your turn without taking actions means there is no “move action”. Because why would there be, if you can always do this anyway?
In the PHB, page 192, it says:
When you take the Dash action, you gain extra movement for the current turn. The increase equals your speed, after applying any modifiers. With a speed of 30 feet, for example, you can move up to 60 feet on your turn if you dash.
The Dash action is the closest thing to a “move action” in 5e, but it doesn't allow you to move. It allows you to increase your movement. You can always move, and taking the Dash action only helps you move faster.
We've been talking about moving on your turn always being possible. But outside your turn, it is not so unless you take a specific action.
From the PHB page 193:
Ready
[...]
First, you decide what perceivable circumstance will trigger your reaction. Then, [...] you choose to move up to your speed in response to it. Examples include [...] "If the goblin steps next to me, I move away."
There is something called a reaction which is also available to you. For the purposes of this question, we don't need to dwell on what are the specifics of a reaction, though.
You may do the Ready action to do something on someone else's turn that is normally only possible on your turn, expending your reaction. This includes moving. (Note: this Ready action is not being used with a Dash action, it is being used to just move on another creature's turn.)
According to PHB 189, players have three types of things they can do on their turn: move, take an action, and take a bonus action.
On your turn, you can move a distance up to your speed and take one action. You decide whether to move first or take your action first. ... Various class features, spells, and other abilities let you take an additional action on your turn called a bonus action.
PHB 190 describes the things you can do when you move. Specifically, you can move as far as your speed allows.
On your turn, you can move a distance up to your speed. You can use as much or as little of your speed as you like on your turn, following the rules here. Your movement can include jumping, climbing, and swimming.
Unlike the "action" and "bonus action" described above, movement doesn't have to be a single discrete event. When a player takes an action or a bonus action, their character performs something specific: casting a spell, making an attack, or interacting with objects, for example. On the other hand, movement can be split up into as many different chunks as a player likes. As PHB 190 states,
You can break up your movement on your turn, using some of your speed before and after your action.
Two examples are given on PHB 190:
If you take an action that includes more than one weapon attack, you can break up your movement even further by moving between those attacks.
If you have more than one speed, such as your walking speed and a flying speed, you can switch back and forth between your speeds during your move.
Splitting up your movement on your turn means that it's possible to have multiple periods of movement during your turn. If we were to use the language of actions, a character could have zero, one, two, or even three "move actions" per turn. At that point, it's easier to have characters draw from a pool of possible movement, rather than adopt the discrete language of actions.
PHB 192:
When you take the Dash action, you gain extra movement for the current turn. The increase equals your speed, after applying any modifiers.
The wording of the dash action uses this idea that movement is a pool to draw from at any time during a turn, rather than an action. Note that you "gain extra movement" to spend, not that you gain another "move action" to use.
As someone who has only played and GMed DnD 5th edition, I can assure you that there is no such thing. Reading the rule book with a clean slate and no experience, I have only ever encountered it in forums, this stack or the like.
The same goes for the non-Vancian (fire-and-forget) spell system in 5e, and (understandably!) why people who've had experience with previous editions have some confusion about it, but that's neither here nor there.
If you take a look at the Index of the Player's Handbook in page 315, it says:
move action. See movement
So, ok, there is such a thing as move action, but it redirects you to movement, and in that section of the rules, it does not distinguish movement as a kind of action. Instead, it's just something you can do on your turn.
If it helps, whenever I explain combat to new gamers, I always say: "You have two things you can do on your turn, you can (1) Move and/or (2) take an Action... I lie, there are actually 3, but let's not get into Bonus Actions yet."
"Move action" isn't a term of art in D&D 5e.
On your turn, you can move a distance up to your speed and take one action1.
Normally, the action economy1 presents the following choices in a turn that do not interfere with each other:
Move
Action
(Attack, Cast a spell, Dodge, Disengage, Help, Hide, Ready, Search, Dash, Use an Object)
Bonus action
Reaction
Interact with object
Note: Bonus actions are limited in availability (something has to grant you a bonus action) and reactions are typically often contingent on something else happening. But you can always move, take an action, and interact with an object.
You can take an action, and then move.
Example: My barbarian hits an orc (the poor orc dies due to massive blunt trauma) and then moves 20 feet.
You can move, then take an action
Example: my barbarian moves 20', then hits an orc. This orc got his shield up, and avoided the blow.
My barbarian can move 30 feet, and then Dash an other 30 feet.
(He sees about fifteen more orcs and, like Hector, plies swift knees). The dash is an action that increases the amount of movement on this turn.
My barbarian can Disengage, and then Move (which prevents an opportunity attack).
(The orc who was hoping for an AoO whiffs, and off goes Conan's nephew, who moves away as far as his move speed allows)
If my character were instead a Fighter, he could use his Action Surge2 to:
Attack, then
Disengage, then
Move
Note that he got two actions (One was an attack, one was disengage) and he's now used his Action Surge until he finishes a rest.
If she were a Rogue, she could Attack, and then use her bonus action (Cunning Action3) to disengage, and then move away and grab that glass of beer4 on the way out of the room (Interact with an object)
References:
1PHB page 191-192 (things you can do in combat)
2PHB page 72 (Action Surge, Fighter)
3PHB page 96 (Cunning Action, Rogue)
4PHB page 190 Interacting with Objects around you
Chapter 9: Combat in the 5e PHB (pg. 189) is the best place to look for rules on movement and actions during your turn.
The "Move Action" from previous editions is now just "Movement" and all other actions you could have taken as a separate "Move Action" are now done in tandem with that "Movement" with a few exceptions.
A lot of other answers already go over the actual movement rules in 5th. (Markovchain's answer does a great job) However the "Move Action" in previous editions also included other actions such as object interaction (opening a door, draw/sheathe a weapon, pick up objects, etc...). In 5th edition, these interactions are done in tandem with your movement or action; basically they are now "Free Actions" (using terminology from 3.xe/PF). From personal experience from switching to 3.5e/PF to 5e, getting used to not referring to these interactions as being a "Move Action" took some getting used to for my players and myself.
In the 5e PHB pg 190 under the section "Other Activity on Your Turn"
You can also interact with one object or feature of the environment for free, during either your move or your action. For example, you could open a door during your move as you stride toward a foe, or you could draw your weapon as part of the same action you use to attack
The table "Interacting with Objects Around You" at the bottom of the same page also goes over a lot things that were previously considered having to spend a "Move Action." There are a few exceptions, however, interacting with a second object would require a player's actual action, objects that specifically require a player to use their action, or the DM determines the task would require special care. These exceptions would typically be the "Use an Object" action (pg 193). This is also mentioned in same section under "Other Activity on Your Turn"
It seems to me like you are only missing the word "action" in the PHB
The first page of Chapter 9: Combat, page 189, states
On your turn, you can move a distance up to your speed and take one action.
The emphasis isn't even mine. I think the fact that the word 'move' is bold kinda infers its a kind of action that can be taken.
Personally, I have always rationalized it this way.
Each turn we get 2 "Actions" but one is a special action which can only be converted to a move ... action. I know the word is missing in the PHB, but it is still something that is being done by the player/character. It is clearly an action taken. At least naratively speaking.
The other action is a "regular action" and can be converted to all those other kinds of options like Dodge, Attack, Hide, Cast, Help, Ready, Search, Use Item and ... the un-aptly named Dash action.
I firmly believe that if they had used the word move instead of dash, no one would ever be confused about this subject. Especially since the dash action is in no way different to the move ... action ... every one gets on their turn.
To try and give a not too popular middle ground, I've always coined it as a move action from 3rd Ed all the way until now.
While technically incorrect, if you break down the language, movement should qualify as a type of action. Yes, the rules are very clear otherwise, not disputing that, but there are many situations where the best option is not move anywhere and continue advancing on the problem at hand.
As a hold-over from previous DMs, they've house-ruled that you can spend your movement do something else, so long as the action doesn't fall into bonus actions or free actions and also not additional attacks that you don't already have for one reason for another.
Common examples come from Rogues and Spellcasters who, when they're not moving, feel stagnant, like a Cleric putting up a buff and then a heal or a Sorcerer attempting two spells (all appropriate Concentration checks applying for those situations).
When it comes to this, safest bet is always following the rules, but your table comes first on deciding how to break down these rules for their game that you as a DM provide.
The rules list 5 activities that you can do On Your Turn:
On your turn, you can move a distance up to your speed and take one action.
Bonus Actions
Various class features, spells, and other abilities let you take an additional action on your turn called a bonus action.
...
Other Activity on Your Turn
Your turn can include a variety of flourishes that require neither your action nor your move.
You can communicate however you are able, through brief utterances and gestures, as you take your turn.
You can also interact with one object or feature of the environment for free, during either your move or your action.
...
Reactions
Certain special abilities, spells, and situations allow you to take a special action called a reaction. A reaction is an instant response to a trigger of some kind, which can occur on your turn or on someone else's.
To reiterate, the 5 activities are:
Of these activities only 1 of them is an "Action". This confusion and resulting mistaken assumption that everything you do on your turn is an Action has lead to a lot of fundamental misunderstandings about how 5e works.
There are different rules for actions and bonus actions. You can think of bonus actions as a special way to perform actions. Just be aware that there are different rules and limitations for both of them.
When explaining something you see as a 'fact' to people who disagree as to whether or not that fact is the case, be prepared for blowback. People don't like it when 'facts' are questioned because it disrupts their surety that their understanding of the world is accurate overall, which reminds them that they are in despair 1.
People also don't like being told that they are wrong about something, especially when they believe that the wrongness is obvious or that others see the wrongness as obvious. We put a lot of value on rightness in thinking, and many people expect to be attacked if they are caught out as having been 'stupid'. People are very afraid to be labeled 'stupid'.
All of this defensiveness is exaggerated on the internet, with its lack of faces to read or tone to hear, and with the anonymity it gives people who wish to act uncharitably. People, as much as they hate being made wrong and on the basis of that wrongness being devalued, are quite happy to make others wrong and on the basis of that wrongness devalue them, if they think there can be no retribution.
Therefore, when correcting someone, it is important to assure them this is not the case, that you are not attacking them and wish them no harm. However, you must be subtle. Do not say things like "I don't think you are stupid" or "Take heart! Your value as a person far outweighs any value I assign you on the basis of intellect: even were I to discredit you the latter, I would nonetheless acknowledge the former". People, especially on the internet, will not receive these as statements in earnest.
Instead, be gentle in your phrasing and terms. Put uncertainty into your claims even where there is none, to remove the appearance of power over the person to whom you speak. Take the time to connect with the person and express approval for their reaction to whatever criticism you do give, if appropriate. Ooze as much compassionate, caring tone you possibly can without coming across as 'fake' or 'condescending'. Once you've convinced someone that you are safe and then convinced them to stop being defensive, they can begin listening and changing their opinion. At that point, you don't need citations or aggressive rhetorical arguments or a hundred like-minded persons backing you up, because the other person isn't fighting you anymore.
This is the best way, in terms of helping the person you are seeking to correct, but it is also very emotionally and temporally expensive. It's not always the right tool for the job, especially if it's likely (like in this case as of 2017) that the position is wholly out of ignorance and has, as of yet, no value to the correct-ee whatsoever.
An efficient, low-cost implementation of this option is to treat the exchange similarly to a rules conflict in a game:
whenever I encounter a situation where someone has made an important declaration that I think might be in error, I say something like:
"I think I'm confused." - I always assume that I might be wrong (even when I'm pretty sure I'm not.) I would then follow up with something like "I thought that it was vs. Dex, not Str. What am I missing?"
Then, I gracefully accept whatever answer I am given...
You might not always convince everyone, but ultimately I don't think conversion rate is the best value criterion to use for this sort of discourse.
A formulation to address movement specifically:
"I think I'm confused. I know 3.5 had move actions, but I didn't think 5e did. What am I missing?"
You should trust the person you are talking to do the research from there. You don't need to cite things at them because they are capable of finding the answer themselves without too much work, and they can ask for a citation if they want one. Citations detract from the sincerity of your feigned confusion.
If you absolutely must, you could do the following:
"I think I'm confused. When I read about actions on pg. 190ish of the PHB, I didn't see anything about move actions. I know they are a thing in D&D 3.5, but are they in 5e as well?"
It is desirable to avoid the following:
"I think I'm confused. Page 189 of the Player's Handbook states in part:
Your Turn:
On your turn, you can move a distance up to your speed and take one action.
Since movement and action taking are explicitly called out as separate, it would seem they are not the same, which would seem to invalidate your answer, which states (quoted part of the answer which indicates movement is an action or refers to a 'move action' in a problematic way), which seems to indicate that they are the same. Since it can't be both an action or not an action, you or the PHB must be wrong. What am I missing?
This comes across as aggressive, despite the bookends. You don't need to support your claim so thoroughly when your claim can be evidentiated easily by the other party. It has a certain "let me give you a thorough, itemized list of everything wrong with your post" feel. That's not helpful.
