The acronyms and abbreviations explained:

• Algo — Algorithm. A mathematical formula, used to rank web pages based on the number of backlinks.
• API — Application Programming Interface. In particular Google's Web API, enabling automated queries. It's accessible with a licence key from Google APIs.
• ATF / BTF — Above ~ / Below the Fold. Respectively inside or outside the part of a web page that's visible in the browser window without scrolling.
• BH — Black hat, allegedly "evil" (cowboy films analogy, see also WH)
• BL — Backlink. A link from another web page to your page. Similar to Inbound Link.
• BLA — Block Level Analysis.
• BLOOP / BLOOD — BackLink Over-Optimisation Penalty or ~ Devaluation. Theory about excessive link building having little – or even an adverse – effect on your pages' ranking on search engines.
• Bot — Robot, Spider, Crawler. A program that goes through web sites and gathers information for the crawler's creator, for example to collect sites for Directories and Search Engines.
• CMS — Content Management System.
• CPA / CPL — Cost per Action / ~ Lead. What you pay for a previously specified action by a web user, for example a purchase.
• CPC — Cost per Click. What you are charged for every time someone clicks on your link on someone's web site.
• CPM — Cost per Thousand. How much you have to pay for every 1000 clicks.
• CSS — Cascading Style Sheets. Lists of formatting rules, used to manipulate and easily manage a web site's design.
• CTR — Click Through Rate. The ratio of impressions shown to the number of clicks.
• DHTML — Dynamic HyperText Markup Language. A dynamic (often animated) implementation of HTML.
• Dir — Directory. A web site that list other sites in their respective categories.
• DMOZ — see ODP.
• DOM — Document Object Model.
• EPC — Earnings per Click.
• FFA — Free For All. This is a links page with nothing but links added by visitors.
• G — Google. Currently the largest and – on average – the most popular search engine.
• HTML — HyperText Markup Language. A language used to format web pages.
• IBL — Inbound Link. A link from another web site to your web page. In short: a backlink from "outside".
• IP — Internet Protocol. The rules for sending and receiving messages at the Internet address level. The IP address is the (four byte) number assigned to any computer connected to the Internet.
• JS — JavaScript. An embedded client-side scripting language, particularly useful to create simple dynamic effects.
• KW — Keyword. A single word used to help identify the purpose of a website. Several keywords combined can make up a keyphrase.
• KWD — Keyword Density. The density (in %) of a given keyword or phrase, on a web page.
• LMH — Last-Modified Header. The code preceding a web document showing a browser or a bot how fresh the document's content is. In-depth info…
• Meta (1) — Meta Tag. A tag used for behind-the-scenes purposes, such as providing content to non-human visitors.
• Meta (2) — Meta Search Engine. A Search Engine using data from different sources combined.
• MSN — Microsoft Network
• OBL — Outbound Link. A hypertext link from your web site to another.
• ODP — (Netscape's) Open Directory Project. A large directory of websites, run by volunteers. Their database is used by many across the internet, including the Google Directory.
• OOP — Over-Optimisation Penalty. Theory
• OP — Original poster. Someone who starts a thread on a forum. This term is used in particular when a thread gets a lot of "side note" posts.
• PFI — Pay for Inclusion. The fact you have to pay for your site to get listed on e.g. a Directory.
• PR — (Google's) Page Rank. Calculation
• Recip — Reciprocal Link. A link from one site to another, and back (as opposed to a one-way link).
• RoS — Run-of-site. Sitewide, distributed across many or all pages of one web site.
• SE — Search Engine. A site that searches the web for web pages, based on a given query.
• SEO / SEM — Search Engine Optimisation / ~ Marketing
• SERP — Search Engine Results Page or ~ Position.
• TLA — Temporal Link Analysis. Calculation
• TLD (1) — Top Level Domain.
• TLD (2) — Temporary Link Devaluation. Theory
• URL — Uniform Resource Locator. The address at which a specific resource (web page) can be found.
• WH — White hat, allegedly "fair" (cowboy films analogy, see also BH)
• WR — (Yahoo's) Web Rank. Calculation
• WWW — World Wide Web. Also a common prefix for web page addresses.
• XHTML — eXtensible HyperText Markup Language. A newer and cleaner variant of HTML.
• XML — eXtensible Markup Language. A language to describe and structure data (not to present it).
• Y — Yahoo.