Browsing the PHB, I noticed the 3rd entry of the spellcraft skill's usages:
15 + spell level: Learn a spell from a spellbook or scroll (wizard only). No retry for that spell until you gain at least 1 rank in Spellcraft (even if you find another source to try to learn the spell from). Requires 8 hours.
Playing a wizard and knowing that no other PHB class can learn extra spells through studies (unless I am mistaken), I immediately recalled the rule stating that you need 24 hours to scribe a spell from a scroll or another spellbook to your own. That is what I have been considering 'learning' a spell so far, and now I am confused. Can someone clarify things a bit (preferably) with an example?