Cloaking:
Cloaking is the presentation of alternative pages to a search engine Spider so that it will record different content for a URL than what a human browser would see. Cloaking is typically done to achieve a higher search engine position or to trick users into visiting a site. In such cases cloaking is considered to be Black Hat SEO and the offending URL could be Blacklisted. However, cloaking is sometimes used to deliver personalized content based on a browser’s IP address and/or user-agent HTTP header. Such cloaking should only be practiced with a search engine’s knowledge or it could be construed as black hat cloaking.

Crawler:
Also known as Spider or Robot, a crawler is a search engine program that “crawls” the web, collecting data, following links, making copies of new and updated sites, and storing URLs in the search engine’s Index. This allows search engines to provide faster and more up-to-date listings.

Delisted:
It is also known as banned or blacklisted, a delisted site is a URL that has been removed from a search engine’s Index, typically for engaging in Black Hat SEO. Delisted sites are ignored by search engines.

Doorway Page:
Also known as a gateway page or jump page, a doorway page is a URL with minimal content designed to rank highly for a specific keyword and redirect visitors to a homepage or designated Landing Page. Some search engines frown on doorway pages as a softer form of Cloaking or Spam. However, doorway pages may be legitimate landing pages designed to measure the success of a promotional campaign, and they are commonly allowed in Paid Listings.

Dynamic Content:
Dynamic content is web content such as Search Engine Results Pages (SERPS) that are generated or changed based on database information or user activity. Web pages that remain the same for all visitors in every context contain “static content.” Many e-commerce sites create dynamic content based on purchase history and other factors. Search engines have a difficult time indexing dynamic content if the page includes a session ID number, and will typically ignore URLs that contain the variable “?”.Search engines will punish sites that use deceptive or invasive means to create dynamic content.