I know the story of TeX, but how did LaTeX come about, and come to be the only (as far as I know) system built on top of TeX?
[Tex/LaTex] How did LaTeX come about
latex-projecttex-history
Related Solutions
I'd rather quote Knuth himself (The TeXbook, page 1):
English words like "technology" stem from a Greek root beginning with the letters τεχ...; and this same Greek word means art as well as technology. Hence the name TeX, which is an uppercase form of τεχ.
Insiders pronounce the χ of TeX as a Greek chi, not as an "x", so that TeX rhymes with the word blecchhh. It’s the "ch" sound in Scottish words like loch or German words like ach; it’s a Spanish "j" and a Russian "kh". When you say it correctly to your computer, the terminal may become slightly moist.
After reading some comments to this answer, I think the following quote is also appropriate (it appear just one paragraph below the previous quote):
On the other hand, it’s important to notice another thing about TeX's name: The "E" is out of kilter. This displaced "E" is a reminder that TeX is about typesetting, and it distinguishes TeX from other system names. In fact, TEX (pronounced tecks) is the admirable Text EXecutive processor developed by Honeywell Information Systems. Since these two system names are pronounced quite differently, they should also be spelled differently. The correct way to refer to TeX in a computer file, or when using some other medium that doesn’t allow lowering of the "E", is to type "TeX". Then there will be no confusion with similar names, and people will be primed to pronounce everything properly.
Citing the CTAN LaTeX entry:
LaTeX is a widely-used macro package for TeX, providing many basic document formating commands extended by a wide range of packages. It is a development of Leslie Lamport's LaTeX 2.09, and superseded the older system in June 1994. The basic distribution is catalogued separately, at latex-base; apart from a large set of contributed packages and third-party documentation (elsewhere on the archive), the distribution includes:
– a bunch of required packages, which LaTeX authors are “entitled to assume” will be present on any system running LaTeX; and – a minimal set of documentation detailing differences from the ‘old’ version of LaTeX in the areas of user commands, font selection and control, class and package writing, font encodings, configuration options and modification of LaTeX.
It's published under the LaTeX Project License 1.3 and is considered to be free and changeable. (See LaTeX Project too)
It was developed initially by Leslie Lamport to ease the usage of TeX
(which was designed by Donald E. Knuth also named The Grand Wizard (not to be confused with the name from the infamous and dreadful KKK) in the late 70s/early 80s)
Although there are commercial TeX versions which have to be paid for the majority of users download LaTeX (and XeLaTeX/LuaLaTeX as well as TeX) either as the TeXLive or MikTeX distributions or directly from the CTAN server.
A list of current maintainers of LaTeX2e
and LaTeX 3
core can be found here: LaTeX 3.
A lot of other people design(ed) additions as style oder class packages, all based on the core -- everybody is allowed to use LaTeX and to provide own additions and formats -- that's one of the most thrilling (and sometimes difficult) features of this 'programming' language.
LaTeX users and developers meet in conferences and are organized in global communities such as TUG (TeX User Group), Dante (a German/Austrian TeX user group) and several other local/national groups as well as online like here on TeX.SX, goLaTeX, LaTeX community and some others.
Best Answer
With respect to the first part of the question, in words of Leslie Lamport:
With respect the second part, LaTeX is not the only system (macro package) based in TeX. Mainly you must be aware of the existence of ConTeXt, but see https://www.ctan.org/tex-archive/macros.