Besides belonging to a country, all Hattrick clubs belong to a region as well.
In Sweden, for example, all regions correspond to a provinces and there's a region for the cities Stockholm and Gothenburg. The point is to select a region to which you feel you belong. It's probably the one you actually live in, or then again, you may have some other reason for choosing it. You don't have to consider if it's smarter to choose one region over another - all regions are, and will stay, equally good.
Function of Regions
The most important feature related to the regions is the concept of derby games. Whenever you play a team from the same region, the team playing away will get half of the bonus to midfield given to the home team.
The other important function has to do with the weather. All matches held in the same region will have the same weather. Each region has its own weather, which is updated every day. At the "Region" caption you can see what the weather is like today in your region, and a weather forecast for tomorrow. As we all know, the weather forecast isn't always entirely accurate, but they get it right quite often. The weather isn't selected completely at random every day. It's connected to what the weather was like the day before. If there was rain today, there's a greater probability of rain tomorrow as well, compared to other types of weather.
The chances are exactly the same for rain, sunshine or anything else regardless of which region you choose. No regions have better weather than others. No region is better than any other region.
The regions are also meant to be "fun", so a person belonging to one area can check out how many people from the same area are participating, how many are logged in, etc. Possibly, being the best club in your region might become a challenge, or trying to get as many players from your own region into the national team. There are also regional conferences to discuss all topics concerning the regions, although many of these are inactive.
Longitudes and latitudes may be subject to rounding errors. They are also chosen arbitrarily from within the region. Should you notice a region in the wrong place, please contact the Game Masters.
A list of all HT regions is found here: Category:Regions