NOTE: Not sure of the best way to organize the relationship between MathJax and LaTeX. For now, I'm separating MathJax and LaTeX into separate notes. In the future it might be best to make MathJaX a sub-section of LaTeX.
LaTeX is a document preparation system for high-quality typesetting. It is most often used for medium-to-large technical or scientific documents but it can be used for any form of publishing.
According to Wikipedia:
LaTeX (/ˈlɑːtɛx/ LAH-tekh or /ˈleɪtɛx/ LAY-tekh, often stylized as LATEX) is a software system for document preparation. When writing, the writer uses plain text as opposed to the formatted text found in WYSIWYG word processors like Microsoft Word, LibreOffice Writer and Apple Pages. The writer uses markup tagging conventions to define the general structure of a document, to stylise text throughout a document (such as bold and italics), and to add citations and cross-references.
MathJax is a software stack that uses LaTeX to
typeset mathematical expressions in web browsers or documents.
Essentially it is a subset of LaTeX that only focuses on mathematical syntax.
Depending on the enclosing format, usually markdown or HTML,
some syntax is used to enclose the LaTeX mathemtical expression.
In markdown, the syntax is $SOMESTUFF$ for inline and
$$SOMESTUFF$$ for block.