The focus of this talk will be on computing the point counts
of algebraic varieties, i.e., number of solutions of a system of
polynomial equations over finite fields. The zeta function encodes the
point counts over an infinite tower of finite field extensions and enjoys
the property of being a rational function over $\mathbb{Q}$
. Further, the zeta
function can be recovered from certain invariants of the variety in
question, using an appropriate cohomology theory. I will review the state of the art on efficient algorithms to compute the
zeta function of varieties, including the dimension one case of curves
(covering the works of Schoof, and Pila) and report on our generalisations
for the first cohomology (joint work with Diptajit Roy and Nitin
Saxena) and ongoing work on the second cohomology, which addresses a question
of Edixhoven.