LaTeX is a markup language for describing a document. It can also be defined as a document preparation system. LaTeX is mainly used to create technical or scientific articles, papers, reports, books or PhD thesis.

There are number of LaTeX distributions you can install on Ubuntu. One such distribution is TeX Live.

1. To install Tex Live LaTeX distribution on ubuntu use the following command.

       sudo apt-get install texlive-full  

2. To edit LaTeX documents we need an editor. There are number of LaTeX editors you can find. I recommend Texmaker, a cross platform LaTeX editor. To install Texmaker on Ubuntu use following command.

       sudo apt-get install texmaker  

3. To open Texmaker on Ubuntu use following command.

   texmaker  

4. Now Let's create a simple document using Texmaker. Click on File -> New and insert following lines in the blank document.

   \documentclass{article}  
     
   \begin{document}  
     
     Hello world!  
     
   \end{document}

5. Now save the document as a 'tex' file by clicking File -> Save. Compile the document clicking the arrow Quick Build.
   

You can learn more about LaTeX by refferring this link.