Every character and creature in the D&D game has a number of different abilities and characteristics. A creature’s statistics block (“stat block” for short) summarizes those attributes.
Many published adventures contain stat blocks for the creatures therein as a convenience, preventing you from needing to look up information from one of the core rulebooks (usually the Monster Manual) in order to run the adventure.
Some stat blocks are less detailed than others, sometimes because those characters or creatures are only “bit players” (commoners or other unimportant NPCs) and sometimes because only certain aspects of a creature’s abilities are relevant to the adventure.
For instance, the stat block for a gold dragon would only need to mention that the dragon can breathe underwater if the place where it’s encountered includes a body of water large enough for this ability to be potentially useful.
Following is a summary of the main elements of a statistics block. All the terms used in this summary are discussed in more detail elsewhere.
Name: The word or phrase that identifies the creature. Race and Class: Provided only for characters with levels.
CR: The Challenge Rating of an individual creature of this kind.
Size and Type: The creature’s size category and its type (and subtype or subtypes, if applicable).
HD: The creature’s Hit Dice (and any hit points it gains or loses because of its Constitution modifier).
hp: The creature’s full normal hit point total (usually average rolls on each Hit Die).
Init: The creature’s modifier on initiative checks.
Spd: The creature’s base land speed, followed by speeds for other modes of movement if applicable.
AC: The creature’s Armor Class against most regular attacks, followed by its AC against touch attacks (which disregard armor) and its AC when flat-footed (or at any other time when denied its Dexterity bonus to AC).
Base Atk: The creature’s base attack bonus without any modifiers.
Grp: The creature’s grapple bonus (base attack + size modifier + Str bonus).
Atk: The single attack the creature makes when taking an attack action (modified attack bonus, whether the attack is melee or ranged, how much damage the attack deals, and the weapon used for the attack).
Full Atk: All the physical attacks the creature can make when taking a full attack action (often the same as the Atk entry).
Space/Reach: How large a square the creature takes up on the battle grid and how far its natural reach extends. The vast majority of creatures have a space/reach of 5 ft./5 ft.; as such, a stat block might omit this entry unless it’s different from the “default.”
SA: The creature’s special attacks (some of which may be described in more detail beneath the Skills and Feats paragraph).
SQ: The creature’s special qualities (some of which may be described in more detail beneath the Skills and Feats paragraph).
AL: The one- or two-letter abbreviation denoting the creature’s alignment.
SV: The creature’s saving throw bonuses.
Ability Scores: The creature’s ability scores in the customary order (Str, Dex, Con, Int, Wis, Cha).
Skills and Feats: In a new paragraph, a list of all the creature’s skill modifiers and feats.
Details: Special attacks and special qualities that need further explanation are covered next.
Spells Known: For sorcerers and members of other classes that do not prepare spells.
Spells Prepared: For wizards, clerics, and members of other classes that prepare spells. A cleric’s stat block also includes the domains he has access to (with domain spells asterisked in the list of prepared spells), his deity (if applicable), and the granted powers of his domains.
Spellbook: Optionally (in addition to Spells Prepared), you may wish to provide the contents of a caster’s spellbook in her stat block. (See the sample NPC wizards on page 125 for what this looks like.) This information can be important for an NPC whom the characters might encounter repeatedly over the course of several days (so that she could choose to prepare different spells on different days).
Possessions: A list of items the creature or character is wearing or carrying.
Obviously, any stat block you create for your own use can be as sparse or as detailed as you need it to be. If all that really matters for an encounter is a creature’s hit points, AC, and attack bonus, then those are the only characteristics you need to make note of.
Use your own stat blocks to streamline the action during play by enabling you to have what you need at your fingertips—but don’t feel that your stat blocks have to provide every conceivable statistic for every creature (unless that’s what you want them to do, of course).