Originally posted by: hollowman
what's ACH?
Taken from the Federal Reserve:
The Automated Clearing House (ACH) payments system was designed to allow corporations and consumers to reduce or eliminate the use of paper checks to make routine payments. The ACH system can process large volumes of individual payments electronically, and it has become the largest payments system in the country; in 2000, it processed over 4.8 billion items with a total value of more than $12 trillion. To date, most of the payments transferred over the ACH have represented recurring credit payments intended for the accounts of the receivers. Typical payments are salaries, consumer and corporate bill payments, interest and dividends, and Social Security and other entitlement programs originated by the U.S. Treasury. However, because of the ACH's ability to process large volumes of payments efficiently and its ability to allow an originator to debit the banking account of the payer, it increasingly is used for other types of payments, such as insurance premiums, purchases of stock, and consolidation of corporate cash balances.
Now, contrast that with wire transfer where the banks need to do a lot of manual processing and you'll see why ACH is significantly cheaper to operate and ultimately passed down to the consumer as a free service.