Thai police divided into four categories:
1. Tourist police. No matter how strange it sounds, but this unit is your first friends in case of any unexpected situations. If you lose your passport or being involved into some accident – first thing you got to do is to call Tourist police. First of all there are foreign employees working there, so there might be no misunderstanding.
2. Immigration police. This authority taking everything concerning of visa questions. Occasionally raids foreign company offices, aiming to identify illegal employees and immigrants. Sometimes immigration officers can be surprisingly adequate and useful, of course if deal with them in correct way.
3. Traffic police. They control everything related to transport, vehicle, traffic, etc. Exactly their officers stop you and fine for driving the motorbike without helmet or other traffic rules violation.
4. Police. Simply police, that takes care of any other affairs related to law and order.