Who is a Customer?
You sell your items/services to customers and receive payments from them. You can create and send sales transactions to them. They can be managed in Zoho Books under Sales > Customers.
Who is a Vendor?
You purchase items/services from vendors and pay them. You can record and send purchase transactions to them. They can be managed in Zoho Books under Purchases > Vendors.
If your customer is also a vendor, then you can link the customer and vendor to create the respective transactions.
Learn more about customers and vendors in Zoho Books from the help document.
Online accounting software
for small businesses.