When it has an active connection to the world wide web and it able to surf the interwebs. If you can read this answer...your computer is online.
Whether one is considered a computer geek is very subjective. Generally one who spends a lot of time on a computer and is very knowledgeable about them may be considered a computer geek. Computer programmers are usually considered computer geeks.
is a tablet considered a personal computer
No, a video game is not considered a computer game. A computer game is considered a video game, however.
The circle and line symbol that appears on most computer power buttons is simply the symbol for Power. This is a universal symbol and it used on computers in many countries. It is considered the universal symbol for Power On/Off.
If the ball hits the line, it is considered in.
If the ball touches the line, it is considered in.
is a standard modem considered to be a computer hardware
They would be considered as being computer literate.
A modem allows your computer to connect to a phone line.
The tennis line is considered in if the ball touches any part of the line. It is considered out if the ball lands completely outside the line.
If a tennis ball hits the line, it is considered in.
In volleyball, the ball is considered in if it lands on the line.