The rules text from Making an Attack in the SRD 5.1 (the 2014 rules), with the rules around it and the 2024 (SRD 5.2) text that goes with it.
When you want to grab a creature or wrestle with it, you can use the Attack action to make a special melee attack, a grapple. If you're able to make multiple attacks with the Attack action, this attack replaces one of them.
The target of your grapple must be no more than one size larger than you and must be within your reach. Using at least one free hand, you try to seize the target by making a grapple check instead of an attack roll: a Strength (Athletics) check contested by the target's Strength (Athletics) or Dexterity (Acrobatics) check (the target chooses the ability to use). If you succeed, you subject the target to the grappled condition. The condition specifies the things that end it, and you can release the target whenever you like (no action required).
Escaping a Grapple. A grappled creature can use its action to escape. To do so, it must succeed on a Strength (Athletics) or Dexterity (Acrobatics) check contested by your Strength (Athletics) check.
Moving a Grappled Creature. When you move, you can drag or carry the grappled creature with you, but your speed is halved, unless the creature is two or more sizes smaller than you.
Contests in Combat (from Making an Attack)
Battle often involves pitting your prowess against that of your foe. Such a challenge is represented by a contest. This section includes the most common contests that require an action in combat: grappling and shoving a creature. The GM can use these contests as models for improvising others.
Size Categories (from Movement and Position)
Size
Space
Tiny
2.5 by 2.5 ft.
Small
5 by 5 ft.
Medium
5 by 5 ft.
Large
10 by 10 ft.
Huge
15 by 15 ft.
Gargantuan
20 by 20 ft. or larger
The grappled condition
What a successful grapple does to the target, in both editions:
2014 (SRD 5.1)
A grappled creature's speed becomes 0, and it can't benefit from any bonus to its speed.
The condition ends if the grappler is incapacitated.
The condition also ends if an effect removes the grappled creature from the reach of the grappler or grappling effect, such as when a creature is hurled away by the thunderwave spell.
2024 (SRD 5.2)
While you have the Grappled condition, you experience the following effects.
Speed 0. Your Speed is 0 and can't increase.
Attacks Affected. You have Disadvantage on attack rolls against any target other than the grappler.
Movable. The grappler can drag or carry you when it moves, but every foot of movement costs it 1 extra foot unless you are Tiny or two or more sizes smaller.
The Grappler feat improves grappling in both editions, and a grappled creature is often also restrained by the monster holding it.
How grappling works
A grapple is a special melee attack you make with the Attack action. If you have Extra Attack, it replaces one of your attacks. The target has to be within your reach and no more than one size larger than you, and you need at least one free hand. Instead of an attack roll, you make a Strength (Athletics) check against the target’s Strength (Athletics) or Dexterity (Acrobatics), and it picks which. Win, and it’s grappled.
Grappled means one thing: its speed becomes 0. It can still attack, cast spells and fight back, just not walk away. The grapple ends if you’re incapacitated, if something pulls it out of your reach, or whenever you choose to let go. To break free, it uses its action for an Athletics or Acrobatics check against your Athletics.
You can move while holding it, dragging or carrying it along, but your speed is halved unless it’s two or more sizes smaller than you.
Using grappling well
Grapple, then shove. Use one attack to grapple and another to shove the target prone. Standing up costs movement, and its speed is 0, so it stays down: attacks against it from within 5 feet have advantage, and its own attacks have disadvantage.
Pin the caster. A grappled wizard can still cast, but it can’t walk out of your party’s reach. Holding it next to the fighter is often better than chasing it.
Drag enemies into trouble. Pull a grappled creature into Spirit Guardians, a Spike Growth or a pit. Dragging is at half speed, but it’s movement the target can’t refuse.
Build for it. Barbarians have advantage on Strength checks while raging, and Expertise in Athletics, which rogues and bards can take, makes you hard to beat. Enlarging yourself with Enlarge/Reduce lets you grab bigger creatures and gives advantage on Strength checks.
What changed in 2024
In the 2024 rules, grappling is one of the options of an Unarmed Strike, so it still takes the place of an attack. There’s no contest: the target makes a Strength or Dexterity saving throw (its choice) against DC 8 + your Strength modifier + your proficiency bonus. To escape, it uses an action for a Strength (Athletics) or Dexterity (Acrobatics) check against that same DC.
The Grappled condition also does more now: besides speed 0, the grappled creature has disadvantage on attack rolls against anyone other than you. Dragging it costs you 1 extra foot per foot, unless it’s Tiny or two or more sizes smaller than you.
Common questions
Does grappling use my action?
It uses the Attack action, but only one of its attacks. A fighter with Extra Attack can grapple with one attack and hit with the other, or grapple and then shove.
What can a grappled creature still do?
Almost everything except move. Under the 2014 rules the grappled condition only sets its speed to 0; it can still attack, cast spells and take any action. Being restrained is the much worse condition.
How do you escape a grapple?
Use your action for a Strength (Athletics) or Dexterity (Acrobatics) check against the grappler’s Strength (Athletics). You also get out if the grappler is incapacitated, if you’re moved out of its reach, or if you teleport away with something like Misty Step. Freedom of Movement lets you escape for 5 feet of movement.
How big a creature can I grapple?
No more than one size larger than you. A Medium character can grapple a Large ogre but not a Huge giant, unless something like Enlarge/Reduce makes you bigger.
Do I need a free hand to grapple?
Yes, at least one. A character with a shield and a one-handed weapon has to stow or drop something first.
Can I attack a creature I’m grappling?
Yes. Grappling doesn’t give advantage on its own, but a grappled creature knocked prone can’t stand up, which gives advantage to everyone attacking it from within 5 feet.