The list of types of friend is as long as your arm.
Are they all the same?
Man's Best Friend - that is a Dog.
Very Good Friend - he might be the milkman. (Thomas Fats Waller song)
Well Meaning Friend
The person you've known for years that goes on the back burner for your significant other.
A place holder until you find someone to sleep with.
The third wheel.
Girlfriend: Hey let's go grab a bite to eat.
Boyfriend: Alright sure, lets go.
Boyfriend: You mind if I invite John?
Girlfriend: Who's that?
Boyfriend: He's just a friend of mine.
Girlfriend: Well I only made reservations for two at "insert restaurant".
Ex two: Forever alone.
Be careful around these types of people because they can sneak past you like a ninja. and once they're in its damn hard to get them out.
See best friend if you want someone you can trust