A completely (almost) unadulterated list of all acronyms, initialisms, and common HTTP response codes associated with search engine optimisation

SEO Acronyms

seo-acronym seo-meaning
AJAX Asynchronous JavaScript and XML
“AJAX is the art of exchanging data with a server, and updating parts of a web page – without reloading the whole page.” – W3 Schools
API Application Programming Interface
An application programming interface is a description of the way one piece of software asks another program to perform a service” – Computer World
ASP Active Server Pages
“Microsoft® Active Server Pages (ASP) is a server-side scripting environment that you can use to create and run dynamic, interactive Web server applications.” – Microsoft
B2B Business to Business
Describes commerce transactions between businesses
B2C Business to Customer
Describes commerce transactions between a business and a customer
CGI Common Gateway Interface
“The Common Gateway Interface is a set of rules for running scripts and programs on a Web server. It specifies what information is communicated between the Web server and clients’ Web browsers and how the information is transmitted.” – TechTerms
CMS Content Management System
A content management system is a piece of software that allows users to create, modify, organise, publish or delete data or ‘content’. WordPress, OpenCMS, and Drupal are all examples of content management systems.
CPA Cost Per Action
Cost per action is a metric that measures how much your business pays in order to attain a conversion.” – Wordstream
CPC Cost Per Click
This refers to the actual price you pay in PPC campaigns when somebody clicks (interacts or visits your site) on your advertisement
CPI Cost Per Impression
The actual cost you pay when an advertisement is displayed and (hopefully) viewed.
CPM Cost Per Thousand Impressions
CR Conversion Rate
The percentage of visitors who turn into actual paying customers.
CRO Conversion Rate Optimisation
The act of developing your website to improve the rate of conversion for visitors or potential customers.
CSS Cascading Style Sheet
“Cascading Style Sheets is a simple mechanism for adding style (e.g., fonts, colours, spacing) to Web documents. ” – W3
CTR Click Through Rate
“The percentage of individuals viewing a web page who click on a specific advertisement that appears on the page.” – Investopedia
DNS Domain Name Server
“…is the system used to translate word-based addresses of systems (such as WWW.EXAMPLE.COM) to the numerical IP (Internet Protocol) address of the computer or system that should be located at that address.” – Tucows Domains
FFA Free For All (link pages)
A page that allows submission of links from anyone and anything (software/bots included), usually to negative results (read: penalties).
FTP File Transfer Protocol
“The File Transfer Protocol is a standard network protocol used to transfer computer files from one host to another host over a TCP-based network, such as the Internet.” – Wikipedia
GAP Google Advertising Professional
Now part of the Google Certification Program.
HTML Hypertext Markup Language
The standard markup language used to create web pages
HTTP Hypertext Transfer Protocol
“HyperText Transfer Protocol is the underlying protocol used by the World Wide Web to define how messages are formatted and transmitted.” – Webopedia
IP Internet Protocol
Internet Protocol is the method or protocol by which data is sent from one device to another on a network. Every device on a network must have at least one IP address that uniquely identifies it from all other devices on the network.
ISP Internet Service Provider
KEI Keywords Effectiveness Index
“A mathematical representation of the popularity of a keyword measured in number of searchers (demand), compared to its popularity measured as the number of pages in a search engines index (supply).” – Keeyword
KPI Key Performance Indicator
A measurement for determining the effectiveness of a particular action or activity such as a marketing campaign or individual advertisement.
LSI Latent Semantic Indexing
Simplified somewhat aggressively, Latent Semantic Indexing is a way of analysing data to determine the relationship of the words used to the search term keywords. Rather than ignore data if it doesn’t contain certain keywords, LSI judges the appropriateness of a search result based on the pattern of words used (looking for synonyms and such), much like a human. (Based on Latent Semantic Analysis) Read more here.
MFA Made For Advertisements (or Made For Adsense)
A site that is made purely to persuade visitors to click on one or many advertisements is known as an MFA site.
NAP Name, Address, Phone Number
In local search optimisation it is important to ensure that your NAP is in the same format on every platform it is visible on. Any discrepancies can have an effect on value.
PDF Portable Document Format (Adobe)
PHP Hypertext Preprocessor
“PHP is a popular general-purpose scripting language that is especially suited to web development.” – PHP.net
PPA Pay Per Action
See Cost Per Action (CPA)
PPC Pay Per click
See Cost Per Click (CPC)
PPP Pay Per Post
The act of paying writers or bloggers money to post on a site. Content is usually dictated by the advertiser and fulfilled to strict requirements. See: payperpost.com
PR Pagerank
“PageRank is an algorithm used by Google Search to rank websites in their search engine results. PageRank works by counting the number and quality of links to a page to determine a rough estimate of how important the website is. The underlying assumption is that more important websites are likely to receive more links from other websites.” – Wikipedia
RLT Regional Long Tail
Simply a long-tail keyword that includes a targeted region. For example “Pancake Restaurants in London”
ROI Return On Investment
A performance measurement based on on how much gain can be made by an investor from an investment, or, the amount of money gained from an action or activity compared to how much was spent on that action or activity.
RSS Really Simple Syndication / Rich Site Summary

“Rich Site Summary is a format for delivering regularly changing web content. Many news-related sites, weblogs and other online publishers syndicate their content as an RSS Feed to whoever wants it.” – WhatisRSS
SE Search Engine
If you need me to explain, you shouldn’t be here.
SEM Search Engine Marketing
Marketing based on improving the visibility of websites in search results.
SEO Search Engine Optimisation
See: Search Engine
SERP Search Engine Results Page
The page containing a list of results provided by a search engine from entering a particular search term
SMM Social Media Marketing
The act of using social media to market a website, to improve traffic and visibility. Read more here: Moz’s Guide to Social Media
SMO Social Media Optimisation
“In general, social media optimization refers to optimizing a website and its content in terms of sharing across social media and networking sites.” Wikipedia
SMP Social Media Positioning
Social Media Positioning relates to the knowledge of where your business is in regards to social media, how your customers perceive you and what needs to be done to optimise your social media strategy.
SSI Server Side Includes
A server-side scripting language used almost exclusively for the world wide web.
UI User Interface
“The junction between a user and a computer program. An interface is a set of commands or menus through which a user communicates with a program.” – Webopedia
URI Uniform Resource Identifier
“A URI identifies the name and location of a file or resource in a uniform format. It includes a string of characters for the filename and may also contain the path to the directory of the file.” – TechTerms
URL Uniform Resource Locator
Also known as a web address. The string of characters that refers to the location of a resource on the WWW.
UX User Experience
The emotions, behaviour and attitude of a user when using a particular product, service or system. More detailed definitions found here: allaboutux.org
XHTML Extensible HyperText Markup Language
An extensible markup language based on HTML. It’s like a hybrid of HTML and XML. Currently the HTML standard is HTML 4.0. You could think of XHTML as HTML 5.0, if that makes it easier…
XML Extensible Markup Language
XML is an open standard used to defining data elements in a web page. See PCMag for a more detailed description.

Common HTTP Response Codes

A hypertext transfer protocol (HTTP) status or response code is a code generated by a server hosting a website to give information about a request from a user (or software) attempting to access a resource on that site.

seo-response-code seo-meaning
200 OK (No problems)
301 Resource Moved Permanently (A permanent redirect code to a new domain or location)
302 Resource Moved Temporarily (A temporary redirect code to a new domain or location)
401 Unauthorized Access to Resource (requires authentication)
403 Forbidden (Access not allowed (server understood the request but refuses to fulfill it))
404 Resource (page) not found
503 The server is unavailable (usually a temporary response due to overloading or maintenance)