Tier 1: An individual you consider marriage material and is both physical and mentally attractive.

Tier 2: An individual who you date exclusively and is highly attractive, but you aren't sure or you don't believe you will settle down with this person.

Tier 3: An individual you would not seriously date exclusively date. This person is attractive but is most likely a booty call or a friend with benefits.

Tier 4: An individual you are not physically attracted to sexually, but you consider them a friend.

Tier 5: A lagoon creature who should never see the light of day.

The Tier System is a much symplified version of the 1-10 system of rating attractiveness based upon first impressions. It works as follows:

Tier 0 : Most attractive possible individual who is also rich and famous.
Tier 1 : Most attractive possible individual who is not rich or famous.
Tier 2 : Very attractive but not in the same league as Tier 1 individuals.
Tier 3 : Somewhat unattractive but acceptable in a pinch.
Tier 4 : Completely unattractive and unacceptable in all sexual contexts.