A useful invention is a computer monitor.This is useful in my life because it holds all of diffrent types of information and it helps you learn new things if you search it up. It makes my life easier by not having to ask my parents things or calling somebody and asking them what homework we have I just go on the teachers website if they have one. The person who invented it was Allen B. in the year 1920. A computer monitor looks like a tv and it is black when not used.