A classic example is the Personal Guarantee. When you go into business you will need to make financial commitments to various parties like landlords, vendors, etc. Most of these commitments are promises to pay. The real question is "Who is promising to pay?" Is it your company that is promising to pay or is it you personally that is promising to pay...or is it BOTH.
When you go into business did you form a corporation? LLC? Hopefully you did because those things can give you some legal protections that, if something goes wrong, you'll wish you had.
