From adding on a carport to doing driveway work on your own property you may need a permit. Just saying you did not know can result in a lot of fines work not being passed since it was never approved, and possibly needing that work torn apart and started over.
Whether you have a large building complex needing permits for work, or you have a building project on a home in a small subdivision you need permits for your projects. Many states and counties have different rules for permits and might you need them for something as small as tree work, or a home remodel, etc. Find out the law for your area. There are some companies that will do all of the work and obtain all the permits you need. For example, if you live in Hollywood, Florida you can look up Building Permit Hollywood FL in the phone book or online and you will find the information that you need on who to contact about getting building permits. Leave all of that to permit obtaining companies and let your headache go away.
If you are a present or future home owner or a building contractor for a large construction firm at some time you may need permits. Knowing all of the ins and outs of how to get permits and who you need to talk to along the way from beginning to end can be made much easier with businesses who do strictly that all day. When you live in areas that are popular for vacations and even people who want to move away from the cold you will find an area that is very popular for apartments, building complexes, malls and shopping centers. Areas that often need more construction because more people move there means more permits and more work for the area too.
With so many agencies to talk to and so many municipalities to deal with this often can be a headache for the layperson who does not know the requirements for obtaining a permit or even why you need one. Speak to your local building department if you are not sure about your own area.