The word "a" (to) in a sentence

The following Spanish sentence has "a" in it. Why is it used?.....¿Conoces a mi amigo, Andrés? D. Morton

Hey D. Morton, I'm still learning myself, but I think the "a" is there because, "mi amigo, Andrés" is the object of the sentence AND a person and that requires an "a". Hopefully, someone can confirm. :O)

Ya i agree with you Jon i just did a lesson that said you needed to put an "a" when you talk about a person.

Hey Jon R and mike67, Thanks for the help! After further research, I learned that "a" is also used with pets when a personal attachment is involved. The verb "tener" and the verb form "hay" are the exception when using "a" for a person or personalized object. An "a" is not used after these two verbs. Wow! Another stone in the wall of knowledge.