The Ignore tag can be used to surround sections of code that you temporarily do not wish to execute (i:e want to have the code present on the page yet not be executed).
This is somewhat akin to comenting out code in other languages to prevent execution.
For example-
<cms:show 'Hello ' />
<cms:ignore>
<cms:show 'world' />
</cms:ignore>
will output only Hello and ignore world.
This tag does not take any parameters.
This tag does not set any variables of its own.