system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does my phone screen not respond to pressing when my finger is wet?
gpt
Phone touch screens work (well modern ones) based on capacitance. That is a build up of charge between two conductive materials with an insulator in between. So when you touch the glass with anything conductive (your finger and water included) a small amount of charge builds up on the object you touched it with and on a conductor on the other side of the glass where you are touching it. This is how the phone knows when and where you touch it. 


When you have wet hands, you inevitably get other parts of the screen other than where you are touching wet. The phone doesn't know what is your finger and what is water. All it knows is it is being touched in multiple places. The results is kind of like you smashing your palm all over it, and you can imagine that doesn't work well.