A Web Widget - is a portable chunk of code that can be installed and executed within any separate HTML-based web page by an end user without requiring additional compilation. They are akin to plugins or extensions in desktop applications. Other terms used to describe a web widget include gadget, badge, module, capsule, snippet, mini and flake. Web widgets often but not always use Adobe Flash or JavaScript programming languages.
Source: http://en.wikipedia.org/wiki/Web_widget
Social Media - describes the online technologies and practices that people use to share opinions, insights, experiences, and perspectives. Social media can take many different forms, including text, images, audio, and video. These sites typically use technologies such as blogs, message boards, podcasts, wikis, and vlogs to allow users to interact. A few prominent examples of social media applications are Wikipedia (reference), MySpace (social networking), Gather.com (social networking),YouTube (video sharing), Second Life (virtual reality), Digg (news sharing), Flickr (photo sharing) and Miniclip (game sharing).
Source: http://en.wikipedia.org/wiki/Social_media
Web 2.0 - a phrase coined by O'Reilly Media in 2003 and popularized by the first Web 2.0 conference in 2004, refers to a perceived second generation of web-based communities and hosted services — such as social-networking sites, wikis and folksonomies — that facilitate collaboration and sharing between users. O'Reilly Media titled a series of conferences around the phrase, and it has since become widely adopted. Though the term suggests a new version of the World Wide Web, it does not refer to an update to Web technical specifications, but to changes in the ways systems developers have used the web platform.
Source: http://en.wikipedia.org/wiki/Web_2.0
Algorithm
Mathematical formula used to rank web sites.
Source: http://www.seo-glossary.com/algorithm.html
Spider
A robot sent out by search engines to catalogue websites on the internet. When a spider indexes a particular website, this is known as 'being spidered'.
Source: http://www.seo-glossary.com/spider.html
Stop Word
A stop word is a common word that is ignored by search engines because it does not add to relevancy. Words such as 'the', 'it', 'a', and 'for' are considered stop words are ignored by many search engines.
Source: http://www.seo-glossary.com/stop-word.html
Link Popularity
A measure of both the number and the quality of inbound links. Most search engines take this factor into considering when ranking websites in SERPs. Marketleap is an excellent website to use to check your website's link popularity.
Source: http://www.seo-glossary.com/link-popularity.html
Inbound Link
This is a hypertext link to a page from another site, bringing traffic to that page. Inbound links are used to calculate link popularity.
Source: http://www.seo-glossary.com/inbound-link.html
PageRank
A technical asset of Google, it is an exponential-based value that signifies importance of a webpage. Google allows one to view a site's PR [on an exponential 10-base] using their toolbar.
Source: http://www.seo-glossary.com/pagerank.html
Site Submission
This is the actual process by which a site is directly submitted to a search engine for inclusion into their database. Some search engines charge a certain amount for 'guaranteed inclusion' into their search index.
Source: http://www.seo-glossary.com/site-submission.html
Spamming
While spamming is generally used to refer to unsolicited bulk mail, spamming in regards to search engines refers to the process of manipulating search engines in order to obtain higher rankings. Such techniques are not tolerated by search engines and if caught, will result in being banned from them.
Source: http://www.seo-glossary.com/unique-visitor.html
Unique Visitor
This is a real visitor to a website. It is the best measurement of how many people actually come to a website.
Source: http://www.seo-glossary.com/spamming.html
CSS
Cascading Style Sheet. Used to easily manipulate and effect the design of a webpage.
Source: http://www.seo-glossary.com/css.html
Alt Text
Short form for Alternative Text, it is an property that is used as a placeholder when the image is loading [and for usability purposes]. In the case of image links, it seems to have weight akin to anchor text.
Source: http://www.seo-glossary.com/alt-text.html
Description
Pretty self-explanatory, it is descriptive text which concisely explains the purpose of a page. A meta tag exists for this, and is used by some search engines when displaying the page as a result in SERPS.
Source: http://www.seo-glossary.com/description.html
Ranking
This refers to the process by which search engines display websites so that the most relevant websites appear on the top. Search engine optimization is a technique by which high rankings may be obtained.
Source: http://www.seo-glossary.com/ranking.html