SSL/TLS Explained
High Priority11 min readUpdated July 4, 2026
AI Mock Interview
Practice this topic in a realistic system design interview
Plain HTTP sends data over the network as readable text. Anyone sitting between the client and server, such as someone on shared Wi-Fi, a compromised router, or an ISP, can read the request, read the response, or change the data before it arrives. For anything sensitive, that is not acceptable.
TLS fixes this by turning that exposed connection into a protected one. It is the security layer behind HTTPS, and it is also used for internal service-to-service traffic.
TLS gives you three protections that matter together:
- Confidentiality: outsiders cannot read the traffic.
- Authentication: you are talking to the server you meant to reach.
- Integrity: the data was not changed on the way.
This chapter explains how TLS creates a secure connection and why these protections matter in real system designs.
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