What does it mean when someone plays on the computer all day
Like many things, the most difficult thing is to phrase a question well. Playing on the computer all day could mean a number of things.
Let's suppose this person is on vacation and has blocked out a single day when they will do nothing but enjoy computer games or a specific game on the computer, this means that the person is rather serious about their computer gaming.
Let's say that normally the person leads a healthy normal life where they take part in school, work, relationships, what have you, and on Saturdays do nothing but play computer games. Again, this person has decided to set aside a block of time for one activity.
This person may even be a game critic or salesperson and need to know a lot about a specific game in a short time (though this wouldn't be "play" in the pure sense of the word).
However, I believe this is probably not the situation the poser of the question was referring to. Doing anything "all day" or "nonstop" is in itself unusual and probably not healthy.
The most common answer (I think) would be some degree of computer addiction. Addiction at any degree begins whenever the activity goes beyond the control of the person doing it at any level, or starts to have a negative impact on the person's life that they are unable to control.
If this person has other obligations that are not met, if the person feels weary or regretful or that they should be doing something else but don't really want to or can't seem to leave the computer then this is a sign of some degree of addiction.
You could specifically look for any of the following situations by either asking or observing the following:
Does the person seem to enjoy the computer more than real life? Do they ever express the wish to actually be in the computer world or game? Do they day dream about being on the computer or in this game universe when they should be doing other things?
Do they express a desire to do other things but never get around to it? Do they regret after spending all that time on the computer only to do it again?
Do they set a planned amount of time to use the computer only to ignore that plan and exceed the set time?
Do they end up spending more and more amounts of time on the computer, perhaps "binging" for an entire day or night or playing until they are physically unable to any longer?
Are they delaying things like eating/sleep/exercise or other normal bodily needs to play the computer?
Are they ignoring or neglecting other things they consider important such as school/friends/family/other leisure activities in favor of the computer then later regretting it?
Do they feel out of sorts or uncomfortable when they can't use the computer?
Do they ever try to downplay or understate the amount of time they spend on the computer to themselves or others? Do they ever say they were doing something else when in fact they were playing on the computer?
Has excessive playing on the computer begun to impact any other aspect of their life (work/school/health/relationships etc.)?
Showing any of these conditions alone or together is most likely an indication of some level of computer addiction.
The nature of addiction is much too complex to discuss in a simple question/answer type forum and really should be discussed with a trained professional but taking the first steps to recognize and then address addiction are very easy.
There are a variety of resources available right on the web, including on the wikipedia site itself.
-N