Great question! The 1099-K is required to be reported for merchant transactions that exceed $600. The IRS has defined it as 'payments for goods or services'. So for instance, if you Venmo your friend for your share of a pizza, or use Paypal to send money to your mom in another state, those types of transactions would not be reported on a 1099-K. No need to worry. Some 3rd party processors, such as Paypal, have an option for you to designate if the transaction is for friends and family or for business.
If for some reason you do receive a 1099-K which you believe to be incorrect, or the reported income is not yours, don't panic. This can be rectified. The IRS information page is here: https://www.irs.gov/businesses/understanding-your-form-1099-k