There are many types of these languages, and HTML is one example, which has been adopted for use on the web. These languages were created in the 60's in order to format text for journals, and books. This led to the creation of HTML which became popular, and the idea of "information at your fingertips" by Microsoft.
Browsers are used in order to render HTML code. Browsers can operate on non-html files, but they render it in terms of HTML. This causes line breaks to be ignored, as well as extra spaces. The browser will also render the file in an older version of the render known as Quirks mode. In order to have a file display correctly we need to add markup.
As HTML developed there were never any major standards that were created. This was mostly due to the speed at which it developed. HTML 1.0-3.0 were mostly without a standard. Finally with version 4.0 a real standard was developed. Before this time content and style were used in combination with the HTML. The style information was later taken out of the HTML, so that the styles could be changed and modified easily.