Copypasta is internet slang for any block of text that gets copied and pasted over and over again, typically disseminated by individuals through online discussion forums and social networking sites. The term is an English portmanteau of "copy," "paste" and "pasta." Although it shares some characteristics with spam in the sense they're both unsolicited (and often considered a nuisance), copypastas are mainly spread through human operators whereas the latter is automatically generated by electronic messaging systems.
This simple concept of "manually copying text from one place and pasting it elsewhere" has been in practice since the innovation of basic text-editing commands (copy/cut/paste) in the early 1980s and subsequent rise of spamming in the early 1990s. In 1974, American computer scientist Larry Tesler, widely cited as the pioneer of "cut and paste" commands, first transferred the function into a computer text-editing software.
The origin of the term "copypasta" is unknown; although, some report to seeing the term on Usenet and 4chan imageboards in 2006. Urban Dictionary  posted the earliest available usage of the term on April 20th, 2006. User Elexus defined the term, "An amount of lengthy text that has been repeatedly copied from somewhere and pasted as a reply to an irrelevant subject." The post received more than 170 upvotes in less than 15 years (shown below).
On September 9th, 2009, Redditor Null_Slate launched the /r/copypasta subreddit. Attracting more than 78,000 users in less than 12 years, the subreddit allows users to share text to various copypasta templates.
Nearly a decade later, on September 14th, 2018, Merriam Webster's Dictionary considered "copypasta" in their "Words We're Watching" series. They wrote:
When you're out and about on the Internet, you sometimes see the same thing in multiple places. There's the funny picture of that angry baby again, or the inspirational quote set against the shot of a rocky peak emerging from the clouds, or that plain-text indignant screed about that thing that apparently made several of your Facebook friends identically indignant. That stuff--all that stuff that's been copied over and over--that stuff has a special name: copypasta.
Creepypasta is a popular subgenre of copypasta, which consists of short horror fiction stories and urban legends mainly distributed through word of mouth via online message boards or e-mail. In recent years, some authors have re-appropriated the genre into an effective pretext for bait-and-switch trolling.
I Herd U Liek Mudkips
I Herd U Liek Mudkips is a catchphrase that became popular through its frequent usage on 4chan in the mid-2000s. Variations on the spelling and the addition of “so” to the beginning of the phrase can also be found. Although its meanings are obscure, the phrase is commonly used as an identifier amongst 4chan users outside of the imageboard community, similar to the usage of "The Narwhal Bacons at Midnight" on Reddit.
Navy Seal Copypasta
Navy Seal Copypasta (also known as the Marine Copypasta, "Internet Tough Guy Copypasta” and “Gorilla Warfare Copypasta”) is a facetious message containing a series of ridiculous claims and grandiose threats that portray the poster as an Internet tough guy stereotype. In the original post, the writer claimed to be a former Navy Seal with a long history of combat experiences, using comical typos and hyperboles like "Gorilla Warfare," “300 Confirmed Kills” and “I can kill you in over 700 ways with just my bare hands.” Since its emergence in mid-2012, the copypasta has spawned a variety of spin-off stories, similar to the John Copypasta meme.
How Is Babby Formed?
How Is Babby Formed refers to a popular question posed to the Yahoo! Answers forum about how humans reproduce. The question is known for its awkward phrasing and misspelling of the word "baby." The phrase became a popular source of YouTube remixes, as well as its frequent use as a copypasta.