Movement

To move, you need a speed with an applicable movement mode. A speed specifies how far you can move with a particular movement mode; many humanoids have a walk speed of 30 feet, for example. A movement mode describes how you move, such as by walking or swimming. See the sections on speeds and movement modes below for more details.
When an effect lets you move using a particular speed, create a pool of movement for that speed of the specified amount. You then travel some distance using that speed's movement modes, spending movement from the pool as you go. Each foot of movement traveled costs 1 foot of movement from the pool, and you can't move if you don't have enough movement left in the pool to do so.
When an effect lets you move using "your speed," create a pool of movement for your speed with an initial amount equal to your speed's value, and move as above. If you have multiple speeds, create a pool of movement for each of your speeds. For each foot traveled using a particular speed, deduct 1 foot of movement from that speed's pool and each pool that had at least as much movement remaining.
While it may seem complicated, this system means that movement is commutative: any sequence of valid movements (such as walk 10, fly 30, fly 5, walk 15 in the "multiple speeds" example below) will still be valid after an arbitrary rearrangement.

More Expensive Movement

Sometimes, such as with difficult terrain, it costs more than 1 foot of movement to travel 1 foot. In these cases, the amount of movement you deduct from each pool is increased by the specified amount.

Changes to Speed

Changes to a speed affect that speed's movement pool(s) immediately, and in the same way as the speed itself is effected. For example, if your walk speed is halved, each movement pool associated with your walk speed is also halved. If your walk speed is set to 0, so is the remaining movement in the pools.
An effect that changes "your speed" affects each of your speeds and their movement pools.

Forced Movement

Movement caused by a push, pull, or other external force is called forced movement. An effect that moves you specifies how far you are moved, ignoring difficult terrain and similar hindrances. Forced movement doesn't create or affect movement pools.
Note that an effect with the phrase "when you move" isn't triggered by forced movement. For example, if grappling lets you drag a creature along with you when you move, you don't drag the creature if you are pushed.

Speeds

A speed comprises one or more natural movement modes, zero or more other movement modes, and possibly other benefits. A speed can be used to travel with any of the movement modes it offers, but each foot traveled with a non-natural movement mode costs 1 extra foot of movement.
Speed ▼ Natural Modes Other Modes (+1 Cost)
BurrowBurrowingJumping, sneaking, crawling
ClimbClimbing, jumpingSneaking
CrawlCrawlingJumping, sneaking
FlyFlyingSneaking
HoverFlyingSneaking
SwimJumping, swimmingCrawling, sneaking
TeleportTeleporting
WalkJumping, walkingClimbing, crawling, sneaking, swimming

Movement Modes

Movement Mode ▼
Burrowing
Climbing
Crawling
Flying
Jumping
Sneaking
Swimming
Teleporting
Walking

Examples

Multiple Speeds

Suppose you have a walk speed of 30 feet and a fly speed of 60 feet, and a spell lets you move up to your speed. You start with a walk pool of 30 feet and a fly pool of 60 feet. You could do the following, in order:
  1. Walk 10 feet, after which your walk pool has 20 feet and your fly pool has 50 feet. You deduct 10 from your walk pool because that's the speed you used, and you also deduct 10 from your fly pool because it was bigger than your walk pool.
  2. Fly 30 feet, after which both pools have 20 feet. You deduct 30 from your fly pool because that's the speed you used, but you don't deduct anything from your walk pool, since it was smaller than your fly pool. From here on, any movement will deduct from both pools, because they are now equal in size.
  3. Fly 5 more feet, after which both pools have 15 feet.
  4. Walk the remaining 15 feet, after which both pools are empty.

Moves and Ready Move

Suppose you have a walk speed of 30 feet. At the start of your turn, you have a walk pool of 30 feet. You could do the following:
  1. As the first action on your turn, you take the Move action to walk 10 feet, leaving your walk pool with 20 feet.
  2. You cast misty step, which you use to teleport 25 feet.
  3. You take the Move action again, walking another 10 feet and leaving your walk pool with 10 feet.
  4. You take the Ready action to ready a Move action for when your ally shouts "go!". You end your turn with 10 feet left in your walk pool.
  5. When you hear "go!" later that round, you use a reaction to walk 5 feet. This leaves your walk pool with 5 feet.