Hello Black Dog, and welcome to Seven Forums.
Reputation points is a way to express your thanks to someone that has helped you solve your problem or answered your question to your satisfaction. By doing this, it helps let others know how reliable that member's suggestions are.
Unfortunately, it can bring out the competitive side for some. However, when positive and negative rep points are given appropriately by members, it all works itself out in the end.
Hope this helps,
Shawn