MS Exchange Server and LDAP

MS Exchange Server and LDAP

I am learning now Exchange Server and how to interface it, so my questions
may sound a bit vague or slily.
What is the relation between the Exchange Server and the LDAP server?
Exchange Server uses directory services and LDAP intefaces them. Does that
mean that Exchange Server is using LDAP to implement its functionality?
Also, when using LDAP I have to authenticate myself.
What is the relation between this authentication and the authentication
when I want to read my mail from ExchangeServer?
Thank you