TeX is considered to be one of the data markup languages. It is the main core of the publication set system (computer typesetting). It is used for mathematical or technical text writing. Many different packets have been created on the basis of ΤeΧ. They are aimed to make it easier to process the documents, especially when they have formulas or math equations.
The most famous such a packet is LaTeX. It lets authors focus on the text and leave the typography process to the program. With LaTeX the structured documents are easy to create and manage.
Both formats are available to manage with the set of applications you can find in here. These are web solutions to convert, view, merge and edit TeX and LaTeX files and create mathematical equations. You may need these apps if you are a student and are writing an essay or a term paper, or if you are working on a scientific work or article.
You do not need to set up any software to work with the applications because they function from any browser. And if you want to have their functionality in your product or manage TeX and LaTeX programmatically the Documentation chapter will help to implement it.