Optical followup of gravitational wave events with the Dark Energy Camera during LIGO O1/O2

We present a summary of the DES-GW program to search for electromagnetic counterparts of gravitational wave events during the first two LIGO observing runs from 2015 to 2017. We will describe the decision-making process of whether or not to follow up.a given event, formulation of the observing plan for followup, the image processing pipeline, and lessons learned from followup of four binary black hole mergers and one binary neutron star merger, including how we plan to apply them during the next LIGO observing run.