A mini course on percolation theory

These are lecture notes based on a mini course on percolation which was given at the Jyväskylä summer school in mathematics in Jyväskylä, Finland, August 2009. The point of the course was to try to touch on a number of different topics in percolation in order to give people some feel for the field. These notes follow fairly closely the lectures given in the summer school. However, some topics covered in these notes were not covered in the lectures (such as continuity of the percolation function above the critical value) while other topics covered in detail in the lectures are not proved in these notes (such as conformal invariance).