According to Wikipedia:

Phishers attempt to fraudulently acquire sensitive information, such as usernames, passwords and credit card details, by masquerading as a trustworthy entity in an electronic communication.

In other words, there are websites out there that masquerade as a genuine website, like eBay or Paypal. These fake sites look exactly like the real thing, logos and all. In reality, they are fake, and their sole purpose is to get personal information out of you.

Firefox has built-in phishing protection, and it is enabled by default. Each site that you visit will be compared to a list known phishing sites that are stored on your computer. No information is sent to Mozilla or any third parties. A new list is downloaded every 30 minutes.

If you come across a known phishing site, you’ll be given two options to click on:

• “Get me out of here!” – This will redirect you to the Firefox Start page.
• “Ignore this warning” – You will continue to the suspected phishing site.

To adjust your anti-phishing settings, go to the top of your browser and click Tools > Options:

 

 

In the “Security” section, you’ll find the following:

 

 

Make sure the box labeled “Tell me if the site I’m visiting is a suspected forgery” is checked.

You are then given two choices:

• Check using a downloaded list of suspected sites.
• Check by asking Google about each site I visit.

If you choose to ask Google, you will be have to accept the terms of service:

 

 

So why would you choose to use the Google list? Well, Google’s list of phishing sites will be a little more up-to-date, since the Firefox list is downloaded every 30 minutes.

You also have the ability to contribute to the anti-phishing cause. If you come across a site that you suspect as forgery, go to the top of your browser and click Help > Report Web Forgery:

 

 

A form will appear where you can then report the suspected site.