Search Engine
A web search engine is a tool designed to search for information on the World Wide Web. The search results are usually presented in a list of results and are commonly called hits. The information may consist of web pages, images, information and other types of files.

What is Forum Posting or Signature Posting?
Forum Posting or Signature Posting is a way to get one way quality links, creating a link of your website with target anchor text in the signature line of your postings, is known as signature in the forum, and when we take part on your behalf, related to your website and do posting, reply the old threads, its called Forum Posting Services.

Why I need to take Forum Posting Services?
Forum Posting having link back in signature to your web site provide Direct Traffic to your web site, the person who read your post can visit your web site. It also provides you Direct One Way Incoming links to your web site which is good way to create one way theme based links. Search engines also assume that you are well active in community and they regular index your website as well as give more importance to your web site.

The Purpose of Blog Comments

Blog comments are what make a blog interactive and social. The most popular blogs have a very interactive community who voice their opinions on posts frequently. It's that social aspect that makes blogs such a powerful component of the social web. People like to feel involved. Leaving blog comments allows readers to join in on the conversation about a topic that interests them.

Benefits Blog Reviews?
Gets direct traffic of your website from the blogs having good readers and visitors. Give your site a one way quality incoming links from blog reviews. Blog reviews and links will be permanent and dofollow. Link popularity increase of your web site.  It helps to push the keyword to rank in Search Engine.

Social Bookmarking
Social bookmarking is a method for Internet users to share, organize, search, and manage bookmarks of web resources. Unlike file sharing, the resources themselves aren't shared, merely bookmarks that reference them.
Descriptions may be added to these bookmarks in the form of metadata, so that other users may understand the content of the resource without first needing to download it for themselves. Such descriptions may be free text comments, votes in favor of or against its quality, or tags that collectively or collaboratively become a folksonomy. Folksonomy is also called social tagging, "the process by which many users add metadata in the form of keywords to shared content".
By: wikipedia