Once you've formatted your document you may `debug' it, i.e. browse through the errors (La)TeX reported.
(C-c `) Go to the next error reported by TeX. The view will be split in two, with the cursor placed as close as possible to the error in the top view. In the bottom view, the error message will be displayed along with some explanatory text.
Normally AUC TeX will only report real errors, but you may as well ask it to report `bad boxes' as well.
(C-c C-w) Toggle whether AUC TeX should stop at bad boxes (i.e. over/under full boxes) as well as at normal errors.
As default, AUC TeX will display that special `*help*' buffer containing the error reported by TeX along with the documentation. There is however an `expert' option, which allows you to display the real TeX output.
User Option: TeX-display-help
When non-nil AUC TeX will automatically display a help text whenever
an error is encountered using
TeX-next-error (C-c `).