Why does base64 end with ==?

Related questions

1. Why is base64 used?
2. What is the use of base64?
3. Why is base64 needed?
4. What is the difference between encoders and decoders?
5. What is the role of decoder?
6. Why do we use base 64?
7. What is the point of base64 encoding?
8. What is a base64 image?
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Tags

1. #proper
2. #doesn
3. #complete
4. #final
5. #always
6. #message
7. #encoding
8. #process
9. #length
10. #short
11. #complement
12. #string
13. #character
14. #encoded
15. #answer
16. #required
17. #base64