All about computer security
Preventative measures are all the measures taken to prevent any damage to the computer. when you first see most computers they ask you for a user name and a password, this is a preventative measure because it means only you know the name and the password so only you can log on. this prevents anybody hacking you computer because it was unlocked. A fire wall is also one of these measures because that prevents viruses from easily entering your computer.
Detective measures are the steps that the computers take to find any viruses and any other things that can harm your computer. Anti-virus scanner are a detective measure because they always scan for viruses which means they are trying to detect anything.
Corrective measures are the steps that the computers take to correct the damage done by viruses.