How to use variables inside trigger firings?

Ok, Ive noticed that there is a thing check box for expanded variables in the trigger area.

Does this mean I can store stuff into the variables each time the trigger fires? If so, how?

i.e. each time the trigger goes, the varible goes up one or something like that.

There is an example in the recent forum posting "General: trigger that match more then one line".

What it means is you can use triggers to set variables, by using "send to variable". eg. you might make a trigger set up a monster's name (eg. Variable "monster" = "kobold" ).

Then another trigger might use that variable, by preceding it by a "@".

eg.

The @monster hits you!

A single trigger can only set one variable, but a trigger can use many variables. Aliases can also use variables. eg.

Alias: k = "kill @monster with @weapon"