Stateful Protocol --> A protocol that requires keeping of the internal state on server is known as stateful protocol
Stateless Protocol --> Stateless protocol is a communication protocol in which no information is retained by either sender or receiver
Stateless - HTTP, IP
Stateful - FTP, SMTP, POP3, TCP
TCP is stateful as it maintains connection information across multiple transfers, but TCP is a Transport layer protocol
FTP and POP3 is stateful Application layer protocol