invisible ascii characters???

[rysolag]

are there any ascii characters that are invisible?

thanks

[Yeldarb]

" " (Space)
And also the first few ASCII characters are, like BEL which makes that beeping sound on your computer. Look for an ASCII table.

[fester8542]

HOLD ALT then hit "255" on the number pad, then release ALT

Blank Space

[λ]

There's also the nul byte, which you probably cannot enter (due to the fact that it generally would mess stuff up) ;)