You need to type the right numbers or letters to unlock something. What am I?

I have a point, I can write and draw, but I get shorter every time you use me. What am I? Solve the riddle → I can be sent to someone to tell them something. What am I? Solve the riddle → What has a head but no body, and dies when it burns? Solve the riddle → I am a language without a voice, built from just two characters. My history traveled over sea and land before the internet existed. Solve the riddle → I have a head and a tail, but no body. I can open locks but have no hands. What am I? Solve the riddle →