I have question about antivirus. What do mean phrases "on demand" and "on access". I tried use Google ( define: ) and didn't find explaination.

Sorry, if OffTopic.

I think that you are asking these as type of anti-virus checking mechanisms. Here is what I understand:

On demand : This means that your anti-virus would check for virus in your system, a particular file only when you specifically tell it do so by clicking scan or invoking it in some other way.

On Access : It means that whenever you open any file on your computer, i.e., access it, it is first checked for the presence of virus and only then allowed to open.

Most of the anti-virus nowadays have on-access feature, which protects your system better. But the on-access feature slows down your system and requires that your antivirus stay resident in memory all the time.

Hope this was useful.

Cheers.

I understand. On access - when I execute application (probably virus), antivirus checks for it. On demand - when I check for virus right click -> Scan.

Thanks very much.