A more thorough explanation:

A retainer is an agreement between a client and a lawyer where the client pays the lawyer in advance for future legal services. There are different types of retainers:

A general retainer is when a lawyer agrees to be available to handle a client's case or future legal issues. The client pays the lawyer for reserving their availability, but the lawyer will have further fees for the services performed. This type of retainer is usually used when the lawyer or law firm has special talents or connections with the client.

A security retainer is when the client makes a payment for future legal services, but the money does not go to the lawyer until they earn the compensation. The goal of a security retainer is to ensure that funds are available to pay the lawyer and firm. When the security retainer is paid, it goes into a trust, and not to the lawyer. The lawyer may receive compensation either periodically for services or after finishing the services in the agreement. Sometimes, a client must replace money in the security retainer that is used to pay for lawyer fees. These agreements can entail that the lawyer receives all of the retainer after the services are performed or the client may be able to receive money back or pay more if the lawyer is to bill hourly.

An advance fee retainer is when the client pays the lawyer in advance for specific legal services that the lawyer will perform in the future. The payments can go to the lawyer, not necessarily to a trust or special account. Usually, advance fee retainers are all the compensation for the services. However, in some states, advance payment retainers merely cover expected fees for the future services with the client being responsible for any extra fees that accumulate.

For example, a client may pay a lawyer a general retainer to ensure that the lawyer is available to handle any legal issues that may arise in the future. Another example is a client paying a security retainer to ensure that funds are available to pay the lawyer for future legal services. Lastly, a client may pay an advance fee retainer for specific legal services that the lawyer will perform in the future.

These examples illustrate how a retainer works. A client pays a lawyer in advance for legal services, and the lawyer will perform the services when needed. The type of retainer determines how the payment is made and when the lawyer receives compensation.