Donald Knuth
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.
(Donald Knuth, $\TeX$book, 1984)
Knuth was working on the second volume of his book
"The Art of Computer Programming", but didn't like the look of the galleys?.
He decided to learn type and font design, typography standards and the rules to typeset maths...
...and after 10 years $\TeX$ was born
(and Knuth's book with it).
Typesetting system used for the production of high-quality technical manuscripts.
A macro is a rule that specifies a set of instructions to be executed, possibly with input and outputs, with the advantage of being called as a single statement.
$\TeX$ alone is the "platform" that offers typesetting through a programming language, it's not meant to be used "as is" in the document formatting workflow.
We define macros to extend $\TeX$ capabilities.
Lamport was working on his book during the 80s when $\TeX$ came out.
He started to collect the macros that he designed to make his workflow more efficient.
Eventually his set of macros became the standard typesetting collection known as $\LaTeX$.
Current team of maintainers of the $\LaTeX$ language, developing and maintaining $\LaTeX3$ and $\LaTeX2\epsilon$.
They distribute $\LaTeX$ under a free software license:
the $\LaTeX$ Project Public License (LPPL).
Their site contains a collection of articles and papers related to the project along with other useful resources.