Is TeX necessary if using LaTeX?

Question

I have been using LaTeX for a little over two years now. I mostly use it to prepare homework solutions in mathematics and engineering coursework. I also use it to document my research and writing some reports.

Recently I have started to use it for my resume, because I find the formatting to be significantly more stable than anything I can get using Microsoft Word. However, I have not been able to find a satisfactory resume class, so I am now modifying a resume class to suit my needs.

To improve the resume class, I am now trying to make some new environments and commands to make the construction more intuitive. The class file that I am modifying appears to be in Plain TeX, which inspires my question.

Are there certain layout and design problems that can only be solved using Plain TeX, or can everything be done using LaTeX?

Answer 1

Plain TeX and LaTeX are different formats, in particular they have different output routine (the code that makes up pages and adds floats and page headers etc).

Apart from the output routine code, almost all the macros defined in Plain TeX are also in LaTeX, so when you look into a class file you may well see code that uses those commands, and in particular includes TeX primitive commands (such as \hbox or \vskip).

To give an example most LaTeX2e packages and classes use the TeX primitive \def to define internal macros rather than the LaTeX command \newcommand (which is itself defined in terms of \def). \def is quicker and if you are defining some specific internal macro, the extra checks that \newcommand does to check the command name has or has not been used are not relevant.