Independent contractors have many names: gig workers, freelancers, contingent workers, contract hires, 1099ers, the alternative workforce... the list goes on.
The type of work can span industry, function, experience level, and geographic distance.
One thing that ties these people together is the 1099 form. It's a tax form that is issued to you by the person who's paying you (often a client/customer) that helps the government track your income.
You may see the 1099-NEC form (for non-employee compensation) or the 1099-MISC form (for miscellaneous income). There are other types of 1099, but they're less common.
Having a 1099 means taxes are not withheld from the payments you receive as income, and you typically don't have access to benefits from an employer. It also can mean that you have more autonomy in when and how you work.