What are TCP and UDP, and what is the difference?

TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are transport layer protocols used for data transmission over a network.

TCP:

• Reliable, connection-oriented.
• Guarantees data delivery in the correct order.
• Uses acknowledgments (ACK), retransmits lost packets.
• Suitable for applications where data integrity is important (e.g., HTTP, FTP).

UDP:

• Connectionless, unreliable.
• Does not guarantee delivery or packet order.
• Lower latency and overhead.
• Used where speed is crucial and some data loss is acceptable (e.g., streaming, online gaming, DNS).

Example in Go for creating a UDP server:

package main

import (
    "fmt"
    "net"
)

func main() {
    addr := net.UDPAddr{
        Port: 12345,
        IP: net.ParseIP("0.0.0.0"),
    }
    conn, err := net.ListenUDP("udp", &addr)
    if err != nil {
        panic(err)
    }
    defer conn.Close()

    buf := make([]byte, 1024)
    for {
        n, clientAddr, err := conn.ReadFromUDP(buf)
        if err != nil {
            fmt.Println("Error:", err)
            continue
        }
        fmt.Printf("Received %s from %s\n", string(buf[:n]), clientAddr)
    }
}