Stateless Protocol does not require the server to retain the server information or session details, where as Stateful Protocol require server to save the status and session information.
HTTP, DNS, UDP are stateless protocal

HTTP (Hypertext Transfer Protocol) is a stateless protocol, which means that the server does not maintain any information about previous requests or the state of the client. Each request from the client is treated as a new, independent request, and the server responds accordingly. To maintain state between requests, HTTP uses cookies, which are small text files that are stored on the client’s computer and can be used to store information about the user’s session. Cookies are not part of the HTTP protocol itself, and their use is optional.

Stateless and stateful are two terms that are commonly used to describe protocols, especially in the context of networking and web development.

Stateless protocols are those in which the server does not maintain any information about previous interactions with the client. Each request from the client is treated as a new, independent request, and the server does not retain any information about the previous requests or the state of the client. Stateless protocols are typically simpler and more scalable, but may be less efficient and may require more bandwidth.

Stateful protocols are those in which the server maintains information about previous interactions with the client. Each request from the client is associated with a session, and the server retains information about the state of the session between requests. Stateful protocols are typically more complex and may require more resources to maintain the session state, but they can provide a more efficient and seamless experience for the user.