Sundry debtors are a group of debtors composed of many individual debtors. They are grouped together because each debtor only makes small or infrequent purchases, and recording all sundry debtors separately would be difficult for bookkeepers. The practice of recording a group of sundry debtors has declined because, while manual ledgers require a separate page for each customer, bookkeeping software makes it easier to record individual debtors. If the customer is frequent and makes substantial charges, then he or she is given a real ledger account and usually acquires some spending privileges from the company.
Every company records its customers and what they buy as part of bookkeeping. A sundry debtor is a customer who might come in once a week or less and buy a few small items. There is no real frequency to his or her purchases and the purchases are not substantial, so the customer is labeled as a sundry debtor. The word "sundry" mean "various" or "miscellaneous", and the term as a whole refers to a debtor who purchases a miscellaneous amount with miscellaneous frequency.
The purpose of recording sundry debtors together instead of counting every debtor as an individual comes down to a decision of convenience. If each sundry debtor were recorded individually, the bookkeeper would have to open an actual debtor account for that person, which would be frustrating for both the bookkeeper and the sundry debtor. The bookkeeper does not want to spend all his or her day entering new account information, and customers do not want to create an account just to buy a few items, so being grouped together benefits both sides.
While the sundry debtors grouping is still used in accounting and bookkeeping, it is used far less than in the days of manual bookkeeping. This is because software is able to quickly make an account for every type of debtor, whereas a manual bookkeeper would have to reserve a whole ledger page for a new debtor and write all the information by hand. While more convenient than in the past, most businesses still keep a sundry debtors account, partly because it is a common practice and partly because it is still quicker than making individual accounts.
The opposite of a sundry debtor is someone who buys a large amount of products with regular frequency. This debtor is spending so much money that an individual account has to be made for this customer. These customers are usually granted spending privileges, such as discounts or expedited shipping, because of their buying frequency.