J.P.C.Greenlees ``Spectra for commutative algebraists.'' 

This paper is an expanded version of lectures given at MSRI 
during the commutative algebra emphasis year 2002-03. The 
idea is to give commutative algebraists an idea about what 
(strictly) commutative ring spectra are, how to construct a 
good category of them, and what use they might be to algebraists.