A Longest Text Ever, commonly abbreviated to just 'LTE', is a webpage with the goal to write the longest wall of text ever. LTEs can take many shapes and forms, but most commonly are hosted on various sites across the web. The earliest known LTE to exist, and the one to introduce the concept is the Flaming Chicken's LTE, created in c. 2004. Despite this, it isn't widely known as no doubt the most popular of these was the WhileTrue LTE, used in various media (such as a JaidenAnimations video) and, for a while, being the first result when searching 'longest text ever' on Google. If you're curious, that title now goes to RainbowFluffySheep's LoTeEv.
LTECenter was brought up by two LTE enthusiasts, first creating LTEs of their own before proceeding to maintain their own version of an updated list of known LTEs, a task attempted by other LTE writers before. In fact, the URL this site is hosted on used to be one of the maintainers' LTE before being repurposed as a general LTE list.