Meaning of Bronze, Silver, etc. in regards to competitive TF2

I am currently looking for a team in TF2. I've look on different forums, and I have noticed that people often speak about "bronze, silver" etc... when they present themselves for joining a team.

I was wondering what is the meaning of this ranking?

Iron and Silver are two of the divisions used in US competitive play. The full list, from best to worst goes:

• Platinum
• Gold (Only in Highlander)
• Silver
• Steel
• Iron

Teams in competitive leagues will play teams from the same division. This means teams will mostly play teams of a similar skill level. Different leagues have different rules for what division a new team can start in but all will bump teams up or down if they perform well or poorly.