What is the primary function of a comma in a sentence?

dmrp201083

isabella.molinelli

pc.k

heather.dow

mamta.rajani

jfox

aorantes

nunesgm

samra.faisal

jocelyn.molina-mancio

labupi89

ymerinogallegos

mwindram

justmurmur

lgilliam

dustin.craighton

patrizia.priano

s.putnikaite

john.hanron