Phishing is a new term which has been going rounds everywhere from forums, blogs, bank sites, etc. It is supposed to be derived from the word fishing. Where just like fishing the hackers or attackers will send out links through spams and other means to as many people as they can and let them fall prey to their attack.
Most of the phishing attacks will disguise as an email from banks, ebay, paypal, etc. Where they will ask for the readers to click on a link for reasons which would be mentioned in the mail, most of the time it will be looking like a friendly mail to check out features or sometimes will tell the users to click on links to make themselves secured from some activity which they had performed.
The best way to avoid phishing attack is by just ignoring such emails by not opening them, although most the ISPs these days have a good filtering programs in their emails which will redirect such emails to spam folders but still some might escape it and will reach your inbox and you should be careful with such emails.
The other most common and threatening and pretty dangerous threat for you and your PC is a keylogging software which might get installed into your PC without you ever been knowing it from bad softwares that you might have installed previously.
Keylogging is nothing but a software or tool where it will monitor all your key strokes that you type on your keyboard and will report those keystrokes to a server somewhere else. This could be used to find your password and other important personal info. Your banking and other key info passwords will be tacked down by key loggers. You need to protect yourself from keylogging software being installed in your PC by installing softwares which will protect from such attacks. If you follow these guidelines you can keep your PC secure from any major security attacks.