Pharming is like a bad guy pretending to be a good guy in the computer world. When you type in a website address, like www.google.com, your computer needs to ask other computers where Google's website is located so it can take you there. Sometimes, a bad guy can make your computer ask the wrong computer, which is really the bad guy's computer, instead of the real one.
This bad guy computer is set up to look exactly like the real website, so it looks safe. But when you enter your personal information, like your username and password, the bad guy records it all. Later, they can use this information to steal your identity or money. This is called pharming.
It's like a thief dressing up as a police officer to trick you into giving them your money or information. Always make sure the website address you are going to is correct and look for the lock icon in the browser bar to make sure it's a secure connection before entering any personal information.