Be careful what you open or click on in your email! Hackers have gotten very good at disguising fake emails containing malicious attachments, or links to malicious websites designed to compromise your computer. They can even make these emails appear to come from trusted sources, such as your bank.
There is even something called “spear phishing,” which is when a hacker targets you specifically in order to entice you to open a file or click a link. Perhaps the hacker learned enough about you from your public Facebook page to create an email that successfully might trick you. This type of social engineering attack is one of the most popular because it often works.
Keep in mind that a bank or most reputable websites will never ask you to click a link and log in (unless it’s a password reset email), so if you do click such a link, double check that you are in the right place before you enter your login credentials.
As for email attachments, never open anything unless you were expecting it and it comes from someone you know.