What is checksum in transport layer?

Related questions

1. How TCP checksum is calculated?
2. What is checksum error?
3. How do I verify checksum of a downloaded file?
4. What is the purpose of checksum TCP field?
5. What is CRC calculation?
6. What is the 3 way handshake?
7. Does UDP use checksum?
8. What are hashes used for?
9. How many errors can CRC detect?
10. How many bytes are the checksum?

Tags

1. #transmitted
2. #numerical
3. #value
4. #scheme
5. #which
6. #simple
7. #checksum
8. #message
9. #usually
10. #detection
11. #calculated
12. #bytes
13. #error
14. #sender
15. #header
16. #based
17. #sends
18. #places
19. #results