There is a lot you can learn on your own and by just attending births, and this is acceptable for many people who are going into doula work. These experiences can offer you information and insight into how to be a doula and there are many good doulas who never receive formal certification. There are, however, benefits to obtaining certification.
Certification is a formal education process that demonstrates a doula is able to meet certain standards determined by a certifying organization. It provides an individual doula with a more official sign of achievement, as well as advancing the profession of the doula.