  These notes are based on the course given by Klaus Fredenhagen at the Les
Houches Winter School in Mathematical Physics (January 29 - February 3, 2012)
and the course "QFT for mathematicians" given by Katarzyna Rejzner in Hamburg
for the Research Training Group 1670 (February 6 -11, 2012). Both courses were
meant as an introduction to modern approach to perturbative quantum field
theory and are aimed both at mathematicians and physicists.
