Markup refers to the sequence of characters or other symbols that you insert at certain places in a text or word processing file
Main categories:
Veni, vidi, vici
Markup can be used to say:
descriptive This is a quote, in Latin, allegedly by Caesar.
presentational Display it in italics with Arial font.
A simple, flexible descriptive text markup format.
The idea is that the markup doesn't tell you what to do (graphically or else) with a piece of text, it tells you what it is, describes it. Another term could be "labeling."
All XML does is provide a nice flexible internationalized way to label the elements of a data structure and ship them around with the labels attached.
Descriptive markup was born in the world of publishing technology, as it had many advantages for serious large-scale publishing.
Makes it possible to define data structure and helps us understand its meaning and context; provides ways to describe the semantics and structure of the information.
Provides means to use grammars taylored for the specific context/need.