There are advantages to playing at both traditional brick and mortar casinos and online casinos. Some players prefer the traditional casino, some prefer online casinos and some players see the advantages of each. If all of your experience is with online casinos then you need to know what differences you will see when you visit a land based casino.
The first and most obvious difference is that there will be live people for you to interact with. This is a stark contrast to the online casino where you do not need to have any contact with other people. It used to be that casinos had dress codes and a code of conduct that needed to be followed. These days people can wear whatever they please and the code of conduct is almost completely gone. Most casinos have either non-smoking or smoking sections. There may also be non-smoking tables within sections. The tables at poker tournaments are generally non-smoking tables, but you can stand up and smoke next to the table. Players are allowed to be loud but not unruly. Offensive behavior is not tolerated and players who behave badly will be first asked to leave and then escorted out if necessary.