If I transfer money between my accounts - will I get any fees for the transfer? What is the difference between ACH and wire?

Question

I transferred money few times between my checking accounts in different banks (Capital One, Ally, Chase, BoA etc). I did not see any fees taken yet and I am not sure if any will be. I checked fees for checking accounts in this banks and it seems all banks have some fees - $15 or $30. But usually they say "domestic wire and international wire". I am not sure if I used "wire" and what it means. Is transferring money between your own account means using "wire"? If not, what is the difference between the way I transfer it between my accounts and wiring? Why I did not get any fees for transfers?

EDIT: So I guess I transfer by default using ACH transfer according to the first answer. Why ACH transfers are free and wires are subject to fees?

Answer 1

Wire transfers are not the same as ACH transfers. I regular transfer money between Chase, Ally, Capital One 360 and Fidelity and have never been charged a fee because I never do wire transfers. (The default for all these banks is ACH; you must explicitly choose wire transfers.)

EDIT: to answer the modified question. https://www.depositaccounts.com/blog/difference-between-wire-transfer-and-ach.html "One of the fastest ways to send money is via wire transfer. Although a wire transfer can take days, in most cases a wire transfer takes place within minutes. It is a direct bank-to-bank transaction that allows you to move money from your account directly into the account of someone else."

"While it may seem similar to a wire transfer, a transaction accomplished with the help of an automated clearing house (ACH) is not the same thing. ... When you arrange for the electronic transfer of funds, all of the information is included in a batch, which is then sent to the clearing house. All of the transactions in the batch are then handled by the clearing house, rather than as a direct bank-to-bank transaction. ... As a result, your money is not available as quickly as it often is with a wire transfer. The ACH process can be more convenient and is less expensive, but it also takes a little bit longer."

Answer 2

Why ACH transfers are free and wires are subject to fees?

Because ACH transfers can be done in batch, and are much easier and cheaper for the banks than wire transfers which must be reviewed individually, are somewhat safer (partly because of this review) and faster, but are more expensive for the banks to process.