Why are my sections numbered 0.1 …?

This happens when your document is using the standard book or report class (or one similar), and you’ve got a \section before your first \chapter.

What happens is, that the class numbers sections as “‹chapter no›.‹section no›”, and until the first \chapter has appeared, the chapter number is 0. (If you use\chapter*, which doesn’t number the chapter it produces, the problem still arises.)

If you’re doing this, it’s possible that the article class is for you; try it and see. Otherwise, put a \chapter before your sections, or do away with section numbering by using \section* instead. An alternative way of avoiding numbering is discussed in “unnumbered sections in the table of contents”.