Lolspeak

A lolcat (pronounced /ˈlɒlkæt/ LOL-kat) is an image macro of one or more cats. The image's text is often idiosyncratic and grammatically incorrect, and is known as lolspeak.

Lolcat is a compound word of the acronymic abbreviation for LOL (laugh out loud) and the word cat. A synonym for lolcat is cat macro, since the images are a type of image macro. Lolcats are commonly designed for photo sharing imageboards and other Internet forums.

British portrait photographer Harry Pointer created a carte de visite series featuring cats posed in various situations in the early 1870s. To these he usually added amusing text intended to further enhance their appeal. Other notable early figures include Harry Whittier Frees and (using mounted animals) Walter Potter.

The first recorded use of the term "lolcat" is from the anonymous imageboard 4chan. The word "Lolcat" was in use as early as June 2006, and the domain name "LOLcats.com" was registered on June 14, 2006. Their popularity was spread through usage on forums such as Something Awful.The News Journal states that "some trace the lolcats back to the site 4chan, which features bizarre cat pictures on Saturdays, or 'Caturdays'." Ikenburg adds that the images have been "slinking around the Internet for years under various labels, but they did not become a sensation until early 2007 with the advent of I Can Has Cheezburger?" The first image on "I CAN HAZ CHEEZBURGER?" was posted on January 11, 2007, and was allegedly from the Something Awful website." Lev Grossman of Time wrote that the oldest known example "probably dates to 2006," but later corrected himself in a blog post where he recapitulated the anecdotal evidence readers had sent him, placing the origin of "Caturday" and many of the images now known by a few as "lolcats" in early 2005. The domain name "caturday.com" was registered on April 30, 2005.

...
Wikipedia