Bitcoinworld enables you to trade bitcoin with other users on internet. Each user has a credit score and an open trading history. When you trade with a trader with very high credit data, you can be assured of trading. You can see the total amount of transactions that the trader has in the near 30 days, the number of people you trust, the average release time, etc. From this data you can determine whether to trade with the trader. It also warns you to leave good data on the deal and build a good trader reputation.