Rules Compendium - Les types d'action

[MoonZar]

Action Types
During a normal round, you can perform a standard action and a move action, or you can perform a full-round action. You can also perform an immediate action or a swift action, and as many free actions as your DM allows. You can always take a move action in place of a standard action. Activities can also be undertaken that are parts of other actions but not actions in and of themselves. In some situations, such as during a surprise round, your activity, and thereby your actions, might be restricted.
Free, full-round, immediate, move, standard, and swift are action types. An action's type tells you how long the action takes to perform within the framework of the combat round. It also tells you how movement is treated.
See Movement, page 90, for more on movement. The Actions in Combat table, page 8, details many possible actions and their parameters.

STANDARD ACTION

A standard action allows you to perform an act that takes a substantial amount of time. The most common type of standard action is a single melee or ranged attack. Other common standard actions include casting a spell, concentrating to maintain an active spell, activating a magic item, and using a special ability.

MOVE ACTION
A move action allows you to move your speed or perform an action that takes a similar amount of time. You can move your speed, climb one-quarter of your speed, draw or stow a weapon or other item, stand up, pick up an object, or perform some equivalent action.
You can take a move action in place of a standard action. For instance, rather than moving your speed and attacking, you could stand up and move your speed (two move actions), put away a weapon and climb one-quarter of your speed (two move actions), or pick up an item and stow it in your backpack (two move actions).
If you move no actual distance in a round -- commonly because you have swapped your move for one or more equivalent actions, such as standing up -- you can usually take one 5-foot step before, during, or after the other actions you're taking.

FULL-ROUND ACTION
A full-round action consumes almost all your effort during a round. Before, during, or after a full-round action in which you don't otherwise move, you can usually take a 5-foot step. The most common type of full-round action is a full attack, which allows you to make multiple melee or ranged attacks in a single round.
Some full-round actions don't allow you to take a 5-foot step. Other full-round actions can be taken as standard actions in situations when you're limited to performing only a standard action during your turn, such as during a surprise round.

FREE ACTION
Free actions consume a very small amount of time and effort. Their impact is so minor that they're considered free. You can perform one or more free actions during your turn. However, the DM can put reasonable limits on what you can really do for free.

SWIFT ACTION
BIRTH OF NEW "FREE" ACTIONS
Halfway into 3rd Edition, while designing Miniatures Handbook, we realized that free actions hid a potential smorgasbord of cool new mechanics. We subdivided the free actions into immediate actions (a free action you can take when it isn't your turn), and swift actions (a free action you can take when it's your turn). However, it wasn't until Expanded Psionics Handbook 's development that the bulb fully brightened. The concept that swift and immediate actions could serve as one more resource available to a player opened up new vistas of possibility, expanding options in the game.
-- Bruce R. Cordell, designer

A swift action consumes a very small amount of time, but it represents a larger expenditure of effort than a free action. You can take a swift action any time during your turn, but you can perform only one swift action per turn.

IMMEDIATE ACTION
An immediate action consumes a tiny amount of time. However, unlike a swift action, an immediate action can be performed at any time during a round, even when it isn't your turn. Using an immediate action on your turn counts as your swift action for that turn. If you use an immediate action when it isn't your turn, you can't use another immediate action or a swift action until after your next turn. You can't use an immediate action when you're flat-footed.

NOT AN ACTION
Some activities are so minor that they aren't even considered free actions. They literally don't take any time at all to do and are considered an inherent part of doing something else.

RESTRICTED ACTIVITY
A few situations make you unable to take a full round's worth of actions. In such cases, you're allowed to take only a single standard action or a single move action, along with allowed swift, immediate, and free actions. You can't take a full-round action and finish that action, but you can start or complete a full-round action by using a standard action.

Source : http://www.wizards.com/default.asp?x=dnd/4pr/20071004a