You wrack your memory and attempt to remember facts or ideas relevant to whatever situation you’re in or puzzle you’re attempting to solve. Make a skill check with a skill relevant to your question (check the skill’s description for what you can use it to recall and what Attribute Modifier to use) against a DC set by the GM based on the difficulty of the question you are attempting to answer.
The GM should not lie to you, regardless of your result, unless there is a running theme of disinformation or mistaken knowledge in the game’s narrative.
Out of combat, this functions as a part of the Discovery process, +++
During combat, you can Recall Knowledge as a Free Action once on your turn, and a Minor Action each time after that. You can do one of the following things with each use of this action:
You can use a Free Action to communicate the highlights of this information to your allies after you recall it.
The following skills can be used to Recall Knowledge, getting information about the listed topics. In some cases, you can get the GM's permission to use a different but related skill, usually against a higher DC than normal. Some topics might appear on multiple lists, but the skills could give different information. For example, Arcana might tell you about the magical defenses of a golem, whereas Crafting could tell you about its sturdy resistance to physical attacks.
The GM might allow checks to Recall Knowledge using other skills. For example, you might assess the skill of an acrobat using Acrobatics. If you're using a physical skill (like in this example), the GM will most likely have you use a mental ability score—typically Intelligence—instead of the skill's normal physical ability score.