snowwhite
What’s the difference between TCP and UDP?
                      Stark
UDP supports four 
connection mechanisms: point-to-point, point-to-multipoint, multipoint-to-point, 
and multipoint-to-multipoint. TCP only supports point-to-point connection.
                      Gemini
TCP guarantees data delivery while UDP only guarantees data transmission. UDP
does not guarantee that data is successfully delivered.      
Sunshine

 TCP is connection-oriented while UDP is connection-free, that is, UDP
requires no link connection before sending data.     
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