What is Phishing?
Phishing is a form of fraud in which the attacker tries to learn information such as login credentials or account information by masquerading as a reputable entity or person in email, IM or other communication channels.
Typically a victim receives a message that appears to have been sent by a known contact or organization. An attachment or links in the message may install malware on the user’s device or direct them to a malicious website set up to trick them into divulging personal and financial information, such as passwords, account IDs or credit card details. Phishing is a homophone of fishing, which involves using lures to catch fish.
Phishing is popular with cybercriminals, as it is far easier to trick someone into clicking a malicious link in a seemingly legitimate email than trying to break through a computer’s defenses. Although some phishing emails are poorly written and clearly fake, sophisticated cybercriminals employ the techniques of professional marketers to identify the most effective types of messages -- the phishing "hooks" that get the highest "open" or click through rate and the Facebook posts that generate the most likes. Phishing campaigns are often built around the year's major events, holidays and anniversaries, or take advantage of breaking news stories, both true and fictitious.
Definition and above information courtesy of TechTarget website