A doula provides continuous non-medical support to a pregnant person and their family, before during and after birth. A doula provides education, emotional and physical support, assistance developing a birthing plan, and assistance with advocacy for the birthing person and partner. A doula does not provide medical support, and works with (does not replace) doctors midwives and nurses.

People hire doulas for many reasons, but in essence there is evidence supporting the fact that having a trusted person, trained in how birth works, continuously present during birth leads to more positive emotional and physical outcomes for the birthing parent and for baby. Lots of evidence is available here:

https://evidencebasedbirth.com/the-evidence-for-doulas/

A doula does not replace a supportive partner! Instead, my role is a doula includes helping your partner to give you the best focused and helpful support that they can. This ranges from teaching pain support measures during a prenatal appointment to making sure your partner is fed through the length of your laber, or that they have a moment to step away and rest when they can without leaving you alone.