Types of Errors

When you create a (La)TeX source file you will make mistakes:

Those that (La)TeX notices

(La)TeX will report an error and stop to await instruction, for example

LaTeX error. See LaTeX manual for explanation. Type H <return> for immediate help. ! Environment itemie undefined. \@latexerr ...for immediate help.}\errmessage {#1} \endgroup l.140 \begin{itemie} ?

Those that it doesn't

Your document won't look as you intended!