Laws vary from state to state, county to county and city to city, so you’ll have to check in your area. But in general, you need a business license to operate a business, even from home. If you are just working at home for your employer, you do not need a business license.
A home-based business is still a business, so all of the usual requirements to operate a business in your state, county or city apply. If you want to open a bank account in the name of your home business, the bank will likely require documentation that you have met the business registration laws in your area. You will need to file a fictitious business name or a DBA, (Doing Business As) in your state as well.
Even if you are working on the Internet, there are tax laws to consider too. In some states, counties or cities, you have to pay an annual tax on your office equipment, including chairs, desks, computers, etc. Some states, Texas for example, require you to charge sales tax, even on services, if you sell to someone within the same state you live in.
The bottom line; A home based business is still a real business even if you work online. Everything you would have to do to comply with the law in a bricks and mortar business, you have to do for a home business.