%\textfont\bffam=\tenbf \scriptfont\bffam=\tenbf in an undergraduate linear algebra course, one learns about inner products on $\bbb r^n$. since the dot product is essentially the only one, they are not very interesting. people actually study a broader class of objects --- {\it symmetric bilinear forms} --- which include what physicists call minkowski space. the desire to classify symmetric bilinear forms leads to investigating their invariants. this talk will discuss symmetric bilinear forms as a case study to motivate the general theory of cohomological invariants, as presented in a forthcoming book by serre, et al. a good portion of this talk will be classical in nature, and so accessible to a more general audience.