Coloring output by using escape sequences is a technique I've known before I started using Linux. That's about two decades now.

But, as I learned today, the tput command provides a much more versatile approach:

bold=$(tput bold)
normal=$(tput sgr0)
echo This is ${bold}bold${normal} and this is not.

tput uses information about the actual terminal to generate the right escape sequences, so it's much better to use tput than to hardcode those.