There are 6 TCP/IP flags
SYN – This flag initiates a connection
ACK – This flag acknowledge received data
FIN – This flag closes a connection
RST – This flag Aborts a connection in response to an error
PST – This flag is used in application where real time data transfer is required.So this flag basically pushes the data immediately.
URG – This flag is used in informing a receiving station that certain data within a segment is urgent and should be given priority.