Blender 3D: Noob to Pro/Basic Animation
|Applicable Blender version: 2.63.|
Frames and Keyframes 
A frame is a snapshot of the scene at one moment in time. An animation consists of displaying a succession of frames representing successive moments in time; if these are shown sufficiently quickly (at least 24 frames per second), the eye is fooled into seeing smooth movement, instead of a succession of still poses.
This is the principle behind both cinema film and digital video. But long before these were invented, it was known that you could make a sequence of drawings on pages of a flipbook, which could then be rapidly flipped by hand to produce an animation.
In live action video, we can capture the frames simply by letting the camera record as the scene unfolds. In hand-drawn animation (cartoons), each frame had to be drawn by a human animator (though there were some shortcut techniques like articulated character pieces, separately-moving scenery layers etc). Actually what would happen was that the most skilled artists would create keyframes representing pivotal points in the animation (starting and ending poses in a character’s movement etc), and the lower-paid assistants would have the job of filling in all the intermediate frames to produce smooth movement between those endpoints.
Computer animation works in a similar way, except here Blender is your lower-paid assistant. You go to crucial points in the timeline of your animation, position and pose your objects/characters appropriately, and tell Blender that this is a keyframe for the relevant transformations (positioning/rotation/scaling) of those objects/characters. Then when you run the animation, Blender will interpolate the specified transformation parameters between keyframes, giving you smooth motion over those intervals.
The Timeline 
At the bottom of the default Blender screen layout is a window called the timeline. This gives you an overview of your animation.
You can zoom the view in and out with the mouse wheel, or scroll left and right with.
The numbers across the bottom are frame numbers, with your animation starting at frame 1. The light grey background indicates the total duration of the animation. The vertical green line is positioned at the current frame time, and the current frame number is also displayed in the box between the start/end values and the transport controls, and at the lower left of the viewport in the 3D view window. Yellow lines indicate where keyframes have been inserted.
You can set the current frame time by clicking withat the desired position. You can hop forward and backward a frame at a time with the left- and right-arrow keys, skip to the next or previous keyframe with the up- or down-arrow keys, and jump immediately to the first or last frame by holding down and pressing left- or right-arrow.
You can also “scrub” by dragging withacross the timeline, which causes the animation to run backwards or forwards at whatever speed you choose, locked to the times across which you drag.
See Also 
- The animation section in the Blender user manual.