What is SPAM in web?

Spam is considered to be electronic junk mail or junk link postings. Some people define spam as Internet slang that refers to unsolicited commercial email or unsolicited link.

Spam is flooding the Internet with many copies of the same link or message, in an attempt to force the link or message on people who would not otherwise choose to receive it. Most spam is commercial advertising, often for dubious products, get-rich-quick schemes, or quasi-legal services.
There are two main types of spam, and they have different effects on Internet users. Email spam targets individual users with direct mail messages. Email spam lists are often created by stealing Internet mailing lists, or searching the Web for addresses.

Another type spamming is link posting. Where user share website link in several location. Link builders looking to build quick and easy links designed to manipulate search engines, scaling their processes as much as possible to build link after link.

In addition to wasting people's time with unwanted link and email, spam also eats up a lot of network bandwidth. Consequently, there are many organizations, as well as individuals, who have taken it upon themselves to fight spam with a variety of techniques. But because the Internet is public, there is really little that can be done to prevent spam, just as it is impossible to prevent junk mail and link posting. However, some online services have instituted policies to prevent spammers from spamming their subscribers.