Trucking/What is authority
What does having your authority do for you and how do you get one?
If you want to operate as a Motor Carrier , you will need operating authority. There are basically two kinds, Private and For Hire.
A construction company who has their own trucks and only hauls their own materials for their own jobs can just register as a Private Carrier. They cannot " hire themselves out " to haul for others.
JB Hunt ( a nationwide for hire carrier) is a good example of a company that makes their living off of hauling just about anything for anybody.
All companies that run commercial trucks will need a USDOT number to be registered with the Feds. The Red Cross is a Private carrier and while they are non-profit..they do have some large trucks. They would only need a USDOT number.
A company like J.B Hunt needs a USDOT number and a MC number which gives them the extra authority to be a for hire carrier.
As far as actually applying to get such an authority, you can go to the FMCSA.org website or there are a bunch of private companies that you can go to and they will do it for you. Dot authority.com , getmyauthority.com , onehourauthority.com. And many more.
To operate Commercial Vehicles without the required authority can get very expensive if ( and when) you get caught.
I hope I have answered your question and presented it in a manner that is easy to understand.