This class system takes many, many forms. The very clothes that people wear are an indicator of what sector of society people where - not just fashion names here, but the styles that they choose to wear. The places where people go, the way they choose to travel, the places that they eat and God damn it, even the food they choose to order! Whatever you do in Thailand, it so often seems that you are being looked at, examined, and your place in the hierarchy is determined. Another example is sport. Bangkok Thais tend to like soccer which would be their favourite sport whereas in other parts of the country, Muay Thai is more popular, at least in terms of participation. Some Bangkokians may consider Muay Thai to be a "peasant's sport". People from poorer provinces with dark skin continue to struggle to be accepted in Bangkok and often find it difficult to get work other than unskilled labour.
Upon meeting someone new, Thais will often ask a few questions based on age, job, education, family and other general information to gauge the other person's status. They will then address them accordingly with pronouns and honorifics that reflect their relative status. Someone of superior status would be addressed as pee followed by their nickname while someone of a lesser status would be addressed as nong and then their nickname. As a foreigner, I don't like to use these terms as I feel they re-enforce aspects of the Thai class system, something that I am not fond of.
Thai people have both a "full name", that is a first name and surname, which tends to be used on all official documents, in employment and generally used at more official occasions. In addition to their real name - or cher jing, all Thais will have a nickname, or cher len. Thai names can be long and may be difficult for a non-Thai to pronounce correctly while the nicknames are conveniently short, usually one syllable. Examples include Nok, Daeng, Noi or Fon. When meeting a Thai person for the first time, they will usually offer you their full name but if you get to know them better and become more familiar with them in a social context you will be probably refer to them using their nickname. Some nicknames are just an abbreviated form of the full name such as the name Suripon which may be shortened to Pon, as a nickname. Many Thai nicknames have a literal meaning and a few of the more common nicknames are listed here.