An LLC is a newer form of corporation... it is best for individually owned companies (sole proprietorships). It stands for: Limited Liability Corporation. It has most of the tax advantages of being Incorporated with alot less paper work. Basically you own the company, but the company owns all the assets and liabilities. You are an owner and a SALARIED employee.
Every company is considered an entity... like a person. If you own a basic company... just go down and file with your state, you are responsible for the actions of your company, equipment, employees, everything. YOU are the one who would get sued. The up side is that the money made is yours to spend when ever.
An LLC is a company that its owners are actually "share holders" and employees. You are a salaried employee (salary set by you by what the job would pay and what income the company can sustain) and are not as liable for incidents/accidents. Your company and its INSURANCE assumes liability for the company. Tax laws are built for business owners, NOT employees. As the owner of an LLC/Inc. you benefit as both. Tax breaks/write-offs and employee benefits (insurance, L & I, unemployment ins., etc.).. and any money not dispursed as salary either stays in the companies holdings or is dispursed to the owners as a DIVIDEND. Oh how I love that word.... DIVIDEND... should I say it again?
There are very distinct differences between an LLC and an Incorporated company... too long to go into here.
Also consider the fact that (AFTER YOU CHECK WITH A CPA) your hobbie is now a showcase for your work and considered a legal write off as advertisement. Just make sure you actually use it for advertising.
It sounds overwhelming but do some research now and you could be up and running in a couple weeks. The dream of owning a company in a field that you love to spend time in is awesome... I have never been happier making money than I am now and am even more excited about tomorrow.
OT: I could also recommend some really good books to put you in the mindset of a business owner. Its all about attitude and understanding that money isn't something to spend it is a tool... like a hammer. When used correctly it is extremely powerful in doing the jobs you ask it to do.