Rendering is the making of the final still
image or animation - it can be very professional-looking and
realistic, with shadows, reflections, textures and transparency like
this render of Suzanne, Blender's mascot.

Blender does
not render continuously since rendering involves a large number of
calculations. This is especially true of animations. A 10 second
animation, for example, with 25 frames per second (still images per
second) would contain 250 images, and each frame might take several
seconds to compute, so the rendering of such an animation might take
several minutes. Rendering a full-length movie might keep a powerful
computer busy all night! Once the animation is done, however, it
should run very smoothly - 25 frames per second is same as the frame
rate used by European televisions.
To control
the rendering process, click the render button
in the properties window. Here
are the most important settings:
Rendering a
still image
Clicking
the 'Image' button or pressing F12 or choosing
Render>Render Image renders a still image of whatever the active
camera sees. By default this will display in full screen but
it is better to choose the 'new window' option for two
reasons. Firstly the rendering process in version 2.5 alpha 2 is a
bit unreliable and is more likely to crash Blender in full screen
mode than in a new window. Secondly when the render is done full
screen you may well click the red close box to dismiss the render,
not realising that this will cause Blender to close completely and
without warning you to save your work. The correct way to dismiss
the render is to press F11, but will you remember this? If
the render is done in a new window then you can close the new window
by pressing the red close box - no problemo.
The
size of the rendered image is set by adjusting the X and Y values
(1920 x 1080 is the resolution of HD video). If you are not yet
ready to do your final, finished render and just want a small, quick
low-quality render then set the percentage to less than 100%.
Rendering a still image does not save it to your hard disk. To save
the rendered image to your hard disk choose Image > Save As
in the render window then specify a file type in the 'Save as'
section (bottom right) choose a location, give a file name (if you
don't include the extension it will be added automatically) then
press the 'Save As' button. It is also possible to specify the
desired file type before you do the render by setting in the Output
section of the Render panel of the Properties window:

Rendering
an animation
Clicking the 'Animation'
button or pressing Ctrl+F12 or choosing Render>Render
Animation will cause an animation to be rendered - this can take
many seconds, minutes or hours according to how long the animation
will last and how big it is.
As previously
mentioned, the dimensions of the animation can be set in the render
panel and it is possible to render at a percentage of less than 100%
if you want a quick, lower quality render because you are not yet
ready to make the final high quality version. Before doing the
rendering, be sure to set the Output file format to a movie format
and not to a still image format such as PNG which is shown in this
image
and which is probably the default. A good choice would be AVI
JPEG since this is a compressed format that should be playable
in standard players such as Windows Media Player. If you leave the
file format as PNG then you will get hundreds of individual files
rather than a single movie file. Note that animation renders ARE
saved to your hard disk, unlike renders of still images, so be sure
to set the folder name (/tmp\ by default) to a folder you have
access to. If you leave the default folder as '/tmp\' then Blender
will save to a folder called 'tmp' on your C drive (it will create
this folder if it does not exist). You do not have access to the C
drive at school so be sure to set the folder to h:\ instead -
this is your personal folder.
When the render
terminates (after several minutes, probably) you should find that a
movie file has been created in your chosen folder. Double-clicking
this file should open it in the associated player.