TeX is one of the lesser known ways of creating documents as it has mostly extremely specialized uses. The typesetting system was designed and written (mostly) by Donald Knuth during the late 1970’s and is a popular choice for typing documents for two main reasons. The first is that documents are standardized across all computers and the results do not change with time. Despite the fact TeX is an old system, the documents still look (relatively) up-to-date, albeit a little lacking in color and design.
The second reason why TeX is so popular, especially in the academic world, is the way it renders maths and mathematical formulas. The range of formulas that can be constructed using TeX is vast and far more flexible than the offerings of other programs (for example Word’s built-in equation editor). The only hindrance to typing up your documents in TeX is that there a very steep learning curve associated with it. TeX is more like a code, with commands and functions and it’s not as easy as simply loading up Word and tapping away.