IRL, or “in real life,” makes the distinction between life in and out of cyberspace. IRL appeared in the 1990s, when the separation between “real life” and online life was more clearly delineated than it is today.

Few abbreviations show off the modern attention span like TL;DR, which stands for “too long; didn’t read.” TL;DR first thrived in the early 2000s on discussion-based forums, where posts considered needlessly long were called out by other users. TL;DR is additionally used as a jocular disclaimer about long text posts. In these cases, the abbreviation is sometimes followed by a brief content summary.

GPOY stands for “gratuitous picture of yourself.” This abbreviation is a shortening of GPOYW, or “gratuitous picture of yourself Wednesday,” which first appeared in 2008 as a Tumblr tag. Unsurprisingly, this tag was used to encourage users to post mid-week selfies. By 2009, it had evolved into GPOY, and it has since expanded to include any image that the poster self-identifies with.

NSFW, meaning “not safe for work,” is a warning that precedes nudity, sexual content, or anything else you wouldn’t want a coworker to see on your screen. NSFW has an earlier slang cousin in NFBSK, or “not for British school kids,” which, in the late '90s, was used jokingly in place of explicit language after a forum user complained that people should watch their language because British school children might be using the site.

SMH stands for “shake (or shaking) my head.” This acronym, which dates back to at least 2004, expresses disbelief or disapproval so great, words do not suffice.

TBH stands for “to be honest” and is used to express personal beliefs. After existing for nearly a decade, TBH has taken on a meaning of its own over the past few years; on social media people hashtag the letters as a means of offering honest opinions about other users.

If you don’t recognize this acronym, it’s no big deal. NBD is used to indicate that something isn’t worth worrying about; it stands for “no big deal.” On the other hand, NBD is also used sarcastically to imply the opposite—that something is, in fact, a big deal.

Feeling assertive about something? IMO, or “in my opinion,” is the abbreviation for you. IMO has been in use since at least the early 2000s and has many lesser-used variants, such as IMHO (“in my humble opinion”) and IMNSHO (“in my not-so-humble opinion”).

JSYK, or “just so you know,” is used to preface information. Emerging around 2005, JSYK is a casual alternative to the classic FYI.