Moduli stack of curves and principal bundles II

In the first talk, we introduced sheaves under Grothendieck topology and categories fibered in groupoids. We will continue to define algebraic stacks and Deligne-Mumford Stacks. The main examples we bear in mind are moduli spaces of curves and moduli stacks of principle bundles over curves. The references are

http://www.math.missouri.edu/~edidin/Papers/mfile.pdf

http://www.math.ubc.ca/~behrend/thesis.pdf