I need a brief (2 or 3 paragraph) general overview of the ACH system,
			by which money is transferred to and from bank accounts in the US.  
			Also, I need the answers to the following specific questions.
			1.  Who can originate the transfer of funds from one account to another?  
			2.  How much does it cost to transfer these funds?  
			3.  If you were running a website and wanted to allow users to
			transfer money to each other using the ACH system (*not* to the
			company behind the website), what kinds of relationships would you
			need to form?  Whom would you contact?
			I've already done the basic google search on "ACH System", and I
			haven't been able to find a single source that answers the questions
			above (a single source might exist, I just haven't found it).  I need
			someone to aggregate the information from a variety of different
			sources, providing links wherever possible.
			

			Hello bonzo,
			I?ll break my answer in 4 parts for your question.
			1. What is ACH?
			Automatic clearing house (ACH) is a nationwide electronic funds
			transfer (EFT) system that provides for the inter-bank clearing of
			credit and debit transactions and for the exchange of information
			among participating financial institutions.
			ACH is one of the groups of processing institutions that have
			networked together to exchange (clear and settle) electronic
			transactions.
			According to Computer world magazine, 
			?The Automated Clearing House is a secure, private electronic payment
			transfer system that connects all U.S. financial institutions. Direct
			paycheck deposits and debit card purchases are two examples of
			electronic fund transfers that go through this network.?
			?Executing ACH payments is cheaper and faster than processing paper
			checks, both business-to-business and business-to-consumer e-commerce
			activities are becoming ever more dependent on the ACH system, thus
			forcing it to evolve.?
			http://www.computerworld.com/softwaretopics/software/appdev/story/0,10801,59309,00.html
			A little history on ACH-
			The ACH was conceived in the early 1970s, when it seemed that the
			increasing volume of paper checks used by businesses and consumers to
			pay their bills would eventually exceed the ability of the existing
			computer systems to process and sort the checks efficiently. The
			Federal Reserve participated in the early discussions and offered to
			provide the computer systems necessary to process and settle the ACH
			items between the depository institutions. In 1974, the regional ACH
			associations formed NACHA to coordinate the establishment of rules to
			facilitate the nationwide clearing of ACH payments.
			The National Automated Clearing House Association (NACHA) develops the
			rule and the standards about ACH transactions.
			http://www.nacha.org/default.htm
			?In 2000, over 4.8 billion payments with a total value of more than
			$12 trillion were processed by ACHs through the Federal Reserve
			System. Typical ACH payments include salaries, recurring bill
			payments, and Social Security benefits?
			http://www.ny.frb.org/aboutthefed/fedpoint/fed31.html
			2. Who can originate the transfer of funds from one account to another
			OR How ACH process works?
			An ACH entry starts with a Receiver authorizing an Originator to issue
			ACH debit or credit to an account. An Originator can be a person, the
			gas company, your local cable company, or your employer. Depending on
			the ACH transaction, the Originator must receive written (ARC, POP,
			PPD), verbal (TEL), or electronic (WEB) authorization from the
			Receiver. Once authorization is acquired, the Originator then creates
			an ACH entry to be given to an Originating Depository Financial
			Institution (ODFI), who can be any financial institution who does ACH
			origination. This ACH entry is then sent to an ACH Operator (usually
			the FED) and is passed on to the Receiving Depository Financial
			Institution (RDFI), where the Receiver's account is issued either a
			credit or debit depending on the ACH transaction.
			More details around this process can be found here. Scroll down after
			clicking on this link for ACH Process-
			http://encyclopedia.thefreedictionary.com/Automated%20Clearing%20House 
			Also check some more details regarding this-
			http://www.echeck.org/overview/comparison/ach.html
			Diagram of ACH Network
			http://www.affirmativeusa.com/electronic_funds_transfer.htm
			3. How much ACH cost?
			A single ACH transaction may cost from 2.5 to 25 cents and this is one
			of the important reasons why ACH has become so popular payment
			mechanism. ACH transactions cost considerably less than wire payments.
			http://www.computerworld.com/softwaretopics/software/appdev/story/0,10801,59309,00.html
			4. How to setup ACH system?
			From your question, it sounds to me that you are asking about how to
			be an ACH. For this, you need to contact all the banks, merchants and
			financial institutions with which you want to setup your ACH process.
			?Simply contact the company in which your debit or credit will
			originate to see if they participate in the ACH program. Your
			employer, power company, insurance company, telephone company, and
			your cable television company are just a few of the firms that may
			participate in the ACH program.?
			http://www.coastalfcu.org/site/conv_automated.html
			Check this answer on Google answers. The question is some what related
			to what you?ve asked, and the answer has some details about how ACH
			can be setup-
			http://answers.google.com/answers/threadview?id=309608
			This site offers ACH processing services-
			http://www.achhub.com
			Check this out too-
			http://www.affirmativeusa.com/financia_institution_achhub.htm
			These are some of the website offering ACH processing-
			http://www.unitedchecks.com/index1024.htm
			http://www.nationaleft.com/
			http://www.epaymentsystems.com/
			Advantage of using ACH system: 
			Fast payments, Less expensive, quick cash flow and more flexible
			Disadvantage: 
			Not enough information is available to the corporations doing electronic payments
			You can check this link on Google Answers to get further details -
			http://answers.google.com/answers/threadview?id=244497
			Search terms used -
			"automated clearing house"
			://www.google.com/search?hl=en&lr=&ie=UTF-8&q=%22automated+clearing+house%22
			automatic clearing house
			://www.google.com/search?hl=en&lr=&ie=UTF-8&q=automatic+clearing+house
			Let me know if this answered your question. In case of any questions,
			feel free to request for clarification.
			Thanks
			netcrazy
			

			Thorough, thoughtful answer with links to backup.  Great answer.