[PF] A question that's probably stupid.

[Voyd211]

Alright, here's a question that copious reading of the core rulebook could not answer.
What, exactly, are Hit Dice, and how do they work with level up? How do they influence HP?
The ONLY explanation of HD is in the common terms section, and it's really vague.

[Baroncognito]

Hit dice are the number of dice you roll to figure out how many hit points you have... mostly. You just count the "max hit points at first level" as rolling too.

If you're a player character, hit dice are equivalent to character level. If you're a single classed player character, it's equivalent to class level.

If you're a monster without character level, hit dice are hit dice.

If you're a monster with character levels, hit dice are monster hit dice plus 1 for every character level.

[Ailowynn]

I had quite the time figuring out HD too, don't feel bad :P. like baroncognito said: for PCs, the number of hit dice equals your level, and the type of hit dice depends on your class. For monsters, HD are pretty much the monster's "level".

For example: a Fighter has a d10 hit die. So each level he gains 1d10+Con mod hit points. At level one he has one hit die; at level 5, five HD. If said fighter took his sixth level in bard he'd have 6 Hit Dice, 5d10 and 1d8.

[Urpriest]

While my Monster Handbook (link in sig) is for 3.5, Pathfinder didn't change the concept of Hit Dice since then, so it's still accurate on this topic. Since most of the handbook is about explaining the role Hit Dice play in the game, you might find it an informative read. Just be wary that some aspects (in particular, ECL) changed in the changeover to PF.

[AttilaTheGeek]

Basically what they said. It's a broader term for level, since it applies to monsters too. If you have rules questions, the simple Pathfinder Q&A thread (http://www.giantitp.com/forums/showthread.php?t=270834) is a great resource.

[Spuddles]

Hit dice is a broad category, under which class levels and monster "levels" fall. Hit dice derived from class level determine all their characteristics via your class- spellcasting, bab, saves, skills, etc

Hit dice from monsters are sort of like monster "class levels", except their type (dragon, undead, etc) decides hit die size, bab progression, base saves, and so forth.