Everyone’s heard of spam as it pertains to emails. Spam isn’t necessarily a malicious message designed to trick you into revealing your credit card number or PayPal login information.

But spam is an unsolicited message, sometimes referred to as junk mail. Spam can be very annoying and relentless in nature, often attempting to convince you to buy something. Sometimes these messages are untruthful, such as those advertising human growth hormone pills (when they actually contain nothing of the sort). Spam also includes phishing which are messages designed to trick you into giving up personal information. Other messages can be legitimate advertisements—nevertheless, you did NOT ask for these solicitations.

Spam arrives in the form of emails, instant messages, and text messages—and it can also affect smartphones.

Spammers buy lists from brokers that continuously harvest email addresses from the web. They also run dictionary attacks, throwing billions of combinations of words and numbers at an email database to find valid address combinations.

Though some emails are obvious spam, such as ones with particular keywords like Viagrasex lifeprescription drug discounts and fast weight loss, other spammy messages are not so obvious; they may appear legitimate or show a sender address of a family member, friend or business associate.

For instance, the sender may appear to be from your bank), with a subject line warning you to urgently update your account information. Similarly, the subject line may not be threatening, such as one referencing “your recent order from Amazon” or “your shipment from DHL,” yet it is not legitimate.

Spammers have found that if enough of these go out all at once, they’ll reach a statistically significant percentage of recipients who will have placed an order from Amazons within the previous 48 hours, or are expecting a delivery from DHL any day.

Here are some tips on how you can fight spam:

  • Be careful with your email address. Don’t supply your email address to sites you’re not sure about, and never post it in a public place.
  • Verify. If you’re not sure if an email is valid, even though it appears to be from your bank, medical carrier, employer, etc., don’t respond to the email. Contact the company or business by phone to verify the email’s validity.
  • Think before you click. Don’t click blindly. Never click on links in unsolicited emails. If you think the email is real, check the link URL to make sure you are being directed to a legitimate site.
  • Open with care. Think twice open attachments that you’re not expecting or from someone who normally wouldn’t send you an attachment.
  • Be cautious. Don’t be fooled by sensational subject lines. Another type of fraud is a subject line claiming you won a prize or are owed money.
  • Ignore it. If the email shows up in your spam or junk folder, chances are it’s spam, so LEAVE IT ALONE!

It’s simple: Never reply to spam.