In terms of search engine marketing, this is the act of getting a search engine to record content for a URL that is different than what a searcher will ultimately see. It can be done in many technical ways.
Spamdexing: synonyms are search spam or search engine spam. The word is derived from two words spam and index. Spamdexing is a practice to push a site up in search results.
This can be done by :
Techniques of spamdexing can be classified into two broad classes:
Various types of content spamming are:
Keyword stuffing in this calculated placement of keywords is done to raise the keyword count, variety, and density of the page.
Hidden / invisible unrelated text in this disguised keywords and phrases are inserted by making them the same color as the background, adding a tiny font size, or hide them within HTML code such as “no frame” sections, ALT attributes, zero-width/height DIVs, and “no script” sections.
Meta tag stuffing using repeated or unrelated keywords in the Meta tags.
Gateway/ doorway pages this technique uses web pages that contain very little content but are instead stuffed with very similar keywords and phrases.
Scraper sites also known as Made for AdSense sites. These are created using various programs designed to scrape SERP. These websites are full of advertising like pay-per-click ads. These also redirect the user to other sites.
Various types of Link spam are:
Link farms makes use of tightly-knit communities of pages referencing each other.
Hidden links:In this highlighted link text is used to rank a webpage higher, for matching phrase.
Sybil attack by creating multiple web sites at different domain names all that link to each other, for example fake blogs known as spam blogs.
Spam blogs also known as splogs. These are fake blogs created solely for spamming.
Page hijacking is done by creating a rogue copy of a popular website which shows contents similar to the original to a web crawler but redirects web surfers to unrelated or malicious websites.
Buying expired domains expired domains are used in page contents to achieve keywords.
Cookie stuffing is achieved by adding an affiliate tracking cookie on a website visitor’s computer without their knowledge. This generates revenue. In SEO world this is considered as fraudulent affiliate sales.