Definition
A business structure created under state law that separates the owner's personal assets from the business's debts and lawsuits. For taxes it is a chameleon: a one-owner LLC is taxed like a sole proprietorship by default, a multi-owner LLC like a partnership, and either can elect to be taxed as an S corporation or a C corporation.
Why it matters
Forming an LLC changes legal exposure, not taxes; by default a freelancer's LLC files the same Schedule C and pays the same self-employment tax as before. The liability shield also only holds if the business is run as a separate entity, with its own bank account and no mixing of personal and business money.