An eCheck, also known as an electronic check or ACH (Automated Clearing House) payment, is a type of electronic fund transfer that enables the transfer of funds between bank accounts. It is an alternative payment method that can be used in place of a credit card processor.

Here is how an eCheck typically works:

1. The customer provides their bank account information (routing number and account number) to the merchant.
2. The merchant enters the information into their payment system, usually an online payment gateway.
3. The payment gateway sends the information to the customer's bank, requesting permission to debit their account for the amount of the transaction.
4. The customer's bank verifies the information and confirms whether there are sufficient funds available in the account.
5. If the funds are available, the bank debits the customer's account and sends the funds to the merchant's bank account.
6. The merchant's bank receives the funds and credits the merchant's account.

The process typically takes 2-3 business days for the funds to clear and be deposited into the merchant's account.

Compared to credit card processing, eChecks can be more cost-effective for merchants as they often have lower transaction fees. Additionally, eChecks may be preferred by customers who do not have or prefer not to use credit cards, or who may not have sufficient credit limits to complete a transaction. However, eChecks do come with some risks, such as the possibility of chargebacks if the customer disputes the transaction, and the potential for fraudulent activity if the customer provides false bank account information.