Spam is email that is sent without being requested. Spam is used mostly to sell services/products, to gather private information (an act called phishing) and to broadcast political or personal views.
Spam is an extremely large issue on the Internet as billions of unwanted messages are sent daily to almost every email account. Spam works by the incredibly small ratio of clicks-to-messages it takes to make money from spam. If a spammer sends a million spam messages and only 100 people click on the link, the spammer will make money. This causes spam to be a very easy (but inconsiderate) way of making money.
Because of the threat of spam, many internet service providers have added large amounts of servers that do nothing but filter spam. There is a law against spam (the CAN-SPAM act) but unfortunately it requires that the spammer be located, which is often very hard to do.
Spam filtering is becoming more advanced, however this is causing spammers to simply send more spam to make up for it. Spammers will also purchase email lists (for very little money) or hijack them to make their job easier. Even worse, selling email lists have become a big business. Because of the threat, it is important that users know how spam works and how they can avoid it.
