Answer:
Thousands of these come together to make a digital image. What is it?
Useful tool for who in darkness dwell. Within you, corrupting like a deadly spell.
The higher I climb, the hotter I engage. I cannot escape from my crystal cage.
What's black when you get it, red when you use it, and white when you're all through with it?
What is it that was given to you, belongs only to you. And yet your friends use it more than you do?
I repeat only the last word you say. The more I repeat, the softer I got. I cannot be seen but can be heard. What am I?