Researchers at Lab 42 asked 500 LinkedIn users that question and many more, and came up with a variety of answers in this infographic. Among the fun facts they uncovered: We found it interesting the way top level executives use the service in vastly different ways from entry-level workers.
BCE stands for  Before the common era . BC means  Before Christ,  or  Before the Messiah.  Both measure the number of years before the approximate birthday of Yeshua/Jesus. Designation of a year in BC and BCE also have identical values. Many people assume that Yeshua/Jesus was born at the end of 1 BCE.
The simplest reason for using BCE/CE as opposed to AD/BC is to avoid reference to Christianity and, in particular, to avoid naming Christ as Lord (BC/AD: Before Christ/In the year of our Lord). Wikipedia, Anno Domini article :