(ə-brēˌvē-āˈshəns) - a shortened or contracted form of a word or phrase, used to represent the whole

• Mr. - Mister (mĭsˈtər) - Used as a courtesy title before the surname, full name, or professional title of a man.
• Mrs. - Missus (ˈmisiz) - Mrs. is the diminutive form of Mistress. It came from the word “mistress” the feminine form of “mister.”

(ăkˈrə-nĭms) - abbreviations that are pronounced as words

• ArcGIS - This is actually a combination of an acronym (ARC) and an initialism (GIS), seldom referred to as an acronysm and even more seldom written acronism (ăkˈrə-nĭzˌəm), and should not to be confused with an anachronism (ə-năkˈrə-nĭzˌəm) which is something different altogether. ArcGIS stands for Aeronautical Reconnaissance Coverage Geographic Information System. Very few people know this, and even fewer care. Now, however, ArcGIS simply refers to the suite of software products produced by ESRI (defined below).
• ARIA - Accessible Rich Internet Applications
• ESRI - Environmental Systems Research Institute - The acronym (pronounced 'ez-ree') is now the preferred usage however, it is still spoken as an initialism, particularly by long-time (i.e. old) ESRI software users.
• FOMO - Fear Of Missing Out - The sense that when you're presented with new information, whether via email, seeing a new article in your Facebook or Twitter feeds, or scrolling through notifications on your phone, that if you don't stop everything and consume it immediately, you're going to miss out on something super important that everybody else in the world knows about but you.
• JSON - (pronounced “jason” according to its inventor, Douglas Crockford) JavaScript Object Notation
• LiDAR - Light Detection and Ranging
• SMART - As used in 'Smart Goals.' Stands for Specific, Measurable, Attainable, Relevant, Time-based. That's all we really know about this having never been able to successfully set a Smart Goal.
• SQL - Stands for Structured Query Language. Even though many people pronounce this as a word (sequel), and thereby making it an acronym, that's wrong. It's really an initialism (see below in the Initialism section) and it should be pronounced that way. (BTW, SEQUEL, was a real acronym back in the 70s when it stood for Structured English Query Language, but was dropped because it was a trademark of an airplane company.)
• SWOT - Strengths, Weaknesses, Opportunities, and Threats - Used as a structured planning method to evaluate these key areas of an organization.
• WYSIWYG - Pronounced (WIZ-ee-wig) - Stands for “What You See Is What You Get.” The phrase was originally created by Flip Wilson's character Geraldine and it inspired researchers at PARC (and elsewhere) to create the acronym for computer software.
• YAGNI - Stands for “You Aren't Gonna Need It” - a principle of extreme programming (XP) that states a programmer should not add functionality until deemed necessary.

(ĭ-nĭshˈə-lĭzˌəms) - abbreviations that are pronounced one letter at a time

• A11Y - Accessibility, the letter “a,” followed by 11 letters, followed by “y”
• aka - also known as
• API - Application Programming Interface
• CIDR - Classless Inter-Domain Routing
• CSS - Cascading Style Sheets
• DYK - Did you know
• DYC - Do you care
• e.g. - from the Latin exemplī grātiā ‎(“for example”)
• EPA - Environmental Protection Agency
• FDGC - See FGDC
• FGDC - (sometimes referred to as FDGC) stands for Federal Geographic Data Committee, see FGDC.gov for more details than you probably want to know, including excruciating details on metadata.
• fka - formerly known as
• FOUC - Flash Of Unstyled Content (also flash of unstyled text or FOUT) - the condition where a web page appears briefly with the browser's default styles prior to loading an external stylesheet, due to the web browser engine rendering the page before all information is retrieved. Related problems include flash of invisible text (FOIT) and flash of faux text (FOFT).
• FTP - File Transfer Protocol
• FYI - For Your Information
• G11N - Globalization, the letter “g,” followed by 11 letters, followed by “n”
• GIS - Geographic Information Systems
• GPS - Global Positioning System
• HTML - HyperText Markup Language
• I18N - internationalization, the letter “i,” followed by 18 letters, followed by “n”
• ICYMI - In Case You Missed It
• IE - Internet Explorer. Many people confuse IE with a web browser. Technically, IE is a Microsoft Internet document viewer. A true web browser will open and display web-based files that conform to the W3C standards. IE opens and displays web-based files that conform to Microsoft's standards.
• i.e. - from the Latin id est (‎“that is”)
• L10N - Localization, the letter “l,” followed by 10 letters, followed by “n”
• nka - now known as
• P13N - Personalization, the letter “p,” followed by 13 letters, followed by “n”
• PhD - Stands for “Doctor of Philosophy” which appears to be a misnomer since most have never taken a philosophy course in their lives.
• PHP - PHP is a very powerful scripting language. In the beginning (1995) “PHP” stood for “Personal Home Page.” But that's changed. It's now a recursive abbreviation and stands for “PHP - Hypertext Preprocessor.”
• PII - Personally identifiable information. Examples include: Full name/usernames, Home address/mailing address, Email address, Credit card numbers, Date of birth, and Phone numbers.
• PIN - Personal Identification Number, used for just about everything in the world.
• SFTP - SSH FTP (File Transfer Protocol), essentially Secure FTP
• SQL - Stands for Structured Query Language and although most people pronounce this as a word, and therefore consider it an acronym, that's wrong. It's really an initialism and it should be pronounced that way.
• SSH - Secure Shell
• TFS - Team Foundation Server - something from Microsoft supposedly to aid in the development of software. Here's an interesting and little known fact. It was originally called “Productivity Optimization Server,” however, confusion resulted since the phrase “Microsoft POS” referred to multiple Microsoft products.
• TL;DR - short for “too long; didn't read” - Internet slang to say that some text being replied to has been ignored because of its length. Variations include: ToS;DR - “Terms of Service; didn't read”, iN;DR - “iNotes; didn't read”,
• TMI - Too Much Information, or Three Mile Island, depending on the context.
• URL - Uniform Resource Locator and is a reference to a resource on the Internet. It's usually just referred to as the web address. Some people will pronounce this as if it was an acronym (earl) but that's wrong, and just sounds stupid.
• UX - Guess this is an initialism with a typo. It's used to mean User Experience.
• VCS - Version Control System, e.g. GIT or SVN
• XKCD - Ok, this is NOT an initialism. According to this, it's “just a word with no phonetic pronunciation.” I'm putting it here, anyway, because this is probably where someone will go to look for it. XKCD (or xkcd) is “A webcomic of romance, sarcasm, math, and language.”