Stateful and stateless are terms used to describe computer systems, applications, and protocols. The key difference between stateful and stateless is whether or not they store data regarding their sessions, and how they respond to requests. Here are some more details:

Stateful:

• Maintains a connection from the beginning to the end of a session to ensure continuous communication.
• Tracks information about the state of a connection or application.
• Has perfect memory or knowledge of previous calls or requests.
• Requires continuous management of the services full lifecycle.
• Highly dependent on the server-side state.
• Usually requires backing storage.
• Can be less secure since the state is maintained.

Stateless:

• Does not save data regarding its sessions.
• Does not store the state of previous transactions.
• Each transaction is made as if from scratch for the first time.
• Does not require the server to retain session information or a status about each communicating partner for multiple requests.
• Simplifies the design of the server.
• Requires fewer resources because the system does not need to keep track of multiple link communications and session details.
• Each communication is discrete and unrelated to those that precede or follow.
• Can be more scalable than stateful designs.

Stateful and stateless can apply to various domains, including architecture, design patterns, protocols, firewalls, and functions. The choice between stateful and stateless depends on what kind of application or system you are building and what you need it to do.