How do people hack your computer?

Question

How do other people gain access to your computer with and without protection systems.

Answer 1

The attackers release worms on the Internet that search for vulnerable computer systems with open ports the worm installs a backdoor Trojan horse once installed allows the remote attacker to control and do just about anything he wants from attacking other crackers, launch a denial of service attack, relay spam, terrorize the legit user of the computer by threatening him on his speakers and moving around his cursor the other ways: trick people into clicking on e-mail attachments, trick people into installing malicious software disguised as legit programs (the attackers counts on stupidity of the user or administrator of the server) the attackers take advantage of exploits that are unpatched by a vendor or the user on the targeted computers system exploits that allow the attacker to escalate privileges to admin or root.

The biggest way is social engineering that's the attacker
conning the user or his target to give him information over
the phone or by other means Kevin Mitnick was the Master
of this technique.

Answer 2

It's usually those people who have no security protection that get hacked. Read the article here: http://www.mbusbyuk.info/security.html and then check out the links page too.
Good Luck!