Article Photos: Why must we buy? Black Friday's powerful pull

A sea of people gather near the electronics section at Target just minutes after the doors open in Muskegon, on Thursday Nov. 22, 2012. (AP Photo/The Chronicle-mlive.com, Libby March)

A sea of people gather near the electronics section at Target just minutes after the doors open in Muskegon, on Thursday Nov. 22, 2012. (AP Photo/The Chronicle-mlive.com, Libby March)