Understanding the color escape code

\033[XXXm is Select Graphic Rendition subset of ANSI escape sequences, \033 is actually ESC character in ascii octal format, \e is equivalent in zsh shell, however, don’t use \e, \e is not recognised in awk nor python.

> echo "\033[31mRed Text\033[0m"
Red Text
> echo "\e[31mRed Text\e[0m"
Red Text

\033[ - Begin the color modifications
CODEm - CODE + m at the end
\e[0m - End the color modifications

code	description
`30, 90`	fg black
`31, 91`	fg red
`32, 92`	fg green
`33, 93`	fg brown
`34, 94`	fg blue
`35, 95`	fg purple
`36, 96`	fg cyan
`37, 96`	fg light grey
`40`	bg black
`41`	bg red
`42`	bg green
`43`	bg brown
`44`	bg blue
`45`	bg purple
`46`	bg cyan
`47`	bg light grey
`0`	reset / normal
`1`	bold
`3`	italic
`4`	underline

> for i in {1..111}
do
    echo '\\e['$i'm' "\e[${i}mtext\e[0m"
done | column

See also: a comprehensive explanation