a lot of arena info!!!!!!

Arena is a set of playlists in Halo: Reach that is supposed to be geared towards the competitive crowd. The main concept is that each person gets rated individually in each game they play and then their skill is judged against the entire population. For the time being, Arena only supports Slayer gametypes, since there are too many intangibles to come up with a fair scoring system for Objective gametypes.

Your Arena rank is only applicable to the specific playlist, which means your Daily Rating, current Division standing, and historical Seasonal performance has no impact on other Arena and non-Arena playlists.

What is a Game Rating?
In the Arena, your Game Rating a numeric representation of how well your performed compared to your teammates and opponents in that single game. If you want to rank up, your goal is to get the highest Rating compared to everyone else in each game you play.

Your rating is visible at the top of the in-game scoreboard as well as in the post-game lobby and here on bungie.net. Everyone on each team is ordered by their rating on the in-game scoreboard, not by their total number of kills like in past Halo games.

How is my Rating calculated?
Simple version: Kills and assists have a positive influence on your Rating. Deaths, betrayals, and losing the game have a negative influence on your Rating.

Harder version: raw_rating = (kills + sa*assists) - (sd*deaths + sb*betrayals)

As of Season 2, the weightings for each of the variables are:

sa = 1
sd = 1/2
sb = 1

In Season 1 and in the Beta, sd was actually 1/3, but it has been changed to 1/2 starting in Season 2.

Complex version: rating = loss_penalty * (1000 + (2000/pi * atan( raw_rating * game_normalization )))

As of Season 2, the values for these variables are:

loss_penalty = 0.96
game_normalization = players_per_team/score_to_win

The lowest (worst) theoretically possible Game Rating is 0, and the highest is 2000. According to the formulas above, the highest possible Rating in Team Arena is 1844 and the highest possible Rating in Doubles Arena is 1705.

It should be noted that these variables can be tweaked from Season to Season. We'll likely see the formula adjusted several times over the first few Seasons. For a more in-depth explanation of the formula, read this.

So I just need to get really high ratings to be put in Onyx, right?
Not necessarily. The only thing your rating is used for is to determine who did better or worse than you in a single game. It doesn't matter whether you have the highest rating with a score of 1700 or the highest rating with a score of 1300. Both will have the same impact on your rank.

Ratings also don't take the skill level of your teammates or opponents into account. If you're in the Silver Division, getting the highest rating in a game against Onyx players has a much larger impact on your rank than getting the highest rating against Iron players.

A more complex formula called TrueSkill is actually used to adjust your rank based on skill level of the players that got a higher and lower rating than you. I'll explain that in a little bit.

What is a Daily Rating?
A Daily Rating is the average rating from your 3 best games for that day. It will appear next to your name in the matchmaking lobby once you've played enough games to earn a Daily Rating. It should be noted that Daily Ratings are for bragging rights only and have no impact on your rank at all.

What are Divisions?
Divisions are a rough estimate of how your skill compares to the skill of everyone else in a given playlist in the Arena. Earn a certain number of ratings in a day to get a Daily Rating. Earn a certain number of Daily Ratings in a Season to get placed into a Division. As of Season 2, you need to play at least 3 games on a given day to get a Daily Rating and you need to get 10 Daily Ratings to be placed into a Division.

These are the Divisions...

Onyx (best)
Gold
Silver
Bronze
Iron (worst)

Once you've been placed in a Division, it becomes visible next to your name in the Matchmaking lobby. It's also visible on your Service Record in-game as well as on bungie.net.

What is a Season?
A Season is a period of time where people can compete for spots in each of the Divisions. Each Season lasts for a month. At the end of each Season, everyone's rank is reset and you will have to start from scratch at the beginning of the next Season. (not all of this info is mine i found some on some other sources.) Heres some other helpful info The best rating you can get is 1999 and the lowest rating you can get is 1. you have to play 3 games in one day to get rated and the best 3 games will get averaged and give you a daily rating. Get rated on 10 days then you will get put into a division and be put in games with players with the similar skill. Hopefully this info helped you finally understand the arena ratings. Got any questions just pm me.

Good post dude!

thanks boosting up my self esteem lol