Hubchallenge is a self imposed challenge like you make a commitment to yourself saying you will write 30 hubs in 30 days, or 100 hubs in 30 days etc. By participating in such hubchallenges, you will be able to write more hubs which ultimately make more money. Without such a challenge, many people may not be able to write more number of hubs. To learn more about this, just do a search on top for "hubchallenge" and you will find hundreds of hubs on this topic. Spend sometime on reading these hubs.