The obvious answer to, “What is a secure PC?,” is, "one that is locked away." However, this is not a helpful answer. This question is most relevant with respect to a computer that is connected to the Internet. In this case, if your computer is connected to the Internet, your answer had better be, “my computer.”
A secure personal computer (PC), when connected to the Internet, is secure from unwanted control and access by unknown and unauthorized external users. A secure PC is one for which passwords are in place and used. The most important password is the administrator’s password. This password should be what is known as a strong password, one that is not easily guessed. A secure PC also has a firewall installed to prevent unauthorized access.
A secure PC has virus protection installed. Virus protection software prevents malicious files from being installed on your computer. Virus software can cause your PC to behave in an unpredictable fashion, cease to function altogether, or do things that you do not want it to do.
A secure PC has it shared files secured. The most common shared files are those that are accessible by the guest account. This account is not password protected by default and usually left that way, but it is important to create a password for this account.
Another way to make for a more secure PC is to change the name of the administrator account. Administrator is the default name; change it to something unique. Be sure to write the new name down, as well as the password. You are likely to need them at some time in the future.
If you use your computer to access the Internet, you should be aware of how to ensure that your PC is a secure PC. Computers do not typically come this way when purchased. If you are uncertain as to how to best set up a secure PC, ask for assistance from a qualified computer professional.