What are the differences between TLS 1.3 and TLS 1.2?

　　Many novice website owners, when configuring HTTPS, will see options like "Enable TLS 1.2" or "Enable TLS 1.3." They then become confused: What are the differences between these two versions? Is newer always better? Will it affect compatibility?

　　Many simply choose "Enable both," believing this is the safest approach. However, TLS 1.3 is not simply an upgrade of TLS 1.2; it has undergone fundamental changes in design philosophy, security model, and performance. Understanding these differences will help you make correct configurations, rather than blindly following trends.

　　The essence of TLS is only one thing: establishing a secure, trusted, and uneavesdroppable communication channel over an insecure network.

　　When a user visits your website, TLS is responsible for authentication (verifying your identity), data encryption (preventing content from being viewed), and data integrity (preventing content from being tampered with). TLS 1.2 and TLS 1.3 both achieve these goals, but in completely different ways.

　　The most obvious difference lies in the "connection establishment speed." In TLS 1.2, the client and server need to perform multiple rounds of "handshakes" before actually transmitting data. Simply put, this involves both parties repeatedly confirming the encryption algorithm to use, the key exchange method, certificate trust, and whether encrypted communication can begin. This process typically requires two or more round trips (RTTs).

　　One of the core design goals of TLS 1.3 is to minimize the round trips during the handshake process.

　　In most scenarios, TLS 1.3 requires only one round trip, and under certain conditions, it can even achieve 0-RTT (zero round trip).

　　For website owners, this means faster initial page load, a significantly improved experience on high-latency networks, and a more pronounced advantage on mobile networks and across regions. For users, it often means "the website feels more responsive."

　　However, TLS 1.3 doesn't simply accelerate by "reducing steps." It makes a crucial decision in its security model: it directly removes all older features that have been proven insecure or easily misused. This is the second key difference between TLS 1.3 and TLS 1.2.

　　In TLS 1.2, for compatibility reasons, many historical algorithms and patterns were retained, such as legacy key exchange methods, static RSA key exchange, and cipher suite combinations that have been proven to be risky. The problem with these isn't that they "would definitely be broken today," but rather that they are complex to configure, easily misenabled, and have a large attack surface—this is where novice website owners are most likely to fall into traps.

　　TLS 1.3 takes a very radical approach: insecure, deprecated, and outdated features are removed outright.

　　The result is no weak encryption algorithms to choose from, no dangerous key exchange methods, and no room for "it can work even if misconfigured." From a security perspective, this is a huge benefit for beginners, as the number of mistakes you can make is reduced.

　　The third very important, but often overlooked, difference is forward security.

　　In TLS 1.2, forward security is not mandatory but "optional." If misconfigured, you might end up using a key exchange method that lacks forward security. This means that if the server's private key is leaked, attackers could potentially decrypt previously captured communication data.

　　However, in TLS 1.3: forward security is mandatory. All connections must use a key exchange mechanism with forward security.

　　For ordinary website owners, this doesn't mean a "theoretical security improvement," but rather that even if the server is compromised in the future, the content accessed by users in the past remains secure. This is especially important for scenarios such as e-commerce, membership systems, and backend logins.

　　The fourth difference lies in the "configuration complexity."

　　Many website owners are overwhelmed by the options when configuring TLS 1.2 for the first time: cipher suites, key exchange, digest algorithms, priority order, etc. A slight mistake can lead to browser warnings, low security ratings, and inaccessibility for some clients.

　　TLS 1.3 greatly simplifies all of this. It transforms many previously optional and combinable parameters into fixed internal design parameters of the protocol. Website owners have less to configure, but security and consistency are actually higher. For beginners, this means: TLS 1.3 is more "user-friendly," but also more secure. The fifth difference relates to compatibility and is one of the most pressing concerns for beginners.

　　Many people worry that enabling TLS 1.3 will prevent older devices from accessing websites. This is a reasonable concern, but it needs to be viewed rationally in the current environment.

　　The reality is that modern browsers fully support TLS 1.3, and compatibility with mainstream systems and devices is very high. Clients that don't support TLS 1.3 are already quite outdated.

　　For example, Google's browser ecosystem prioritizes TLS 1.3 by default.

　　Servers can typically support both TLS 1.2 and TLS 1.3 simultaneously, with clients automatically negotiating the optimal version. In other words, enabling TLS 1.3 does not mean abandoning TLS 1.2.

　　So, how should novice website owners choose in practice?

　　A very safe and mainstream approach is to enable both TLS 1.2 and TLS 1.3 simultaneously, disabling the older protocol version and allowing the client to negotiate automatically. The advantage of this is that modern users enjoy the speed and security of TLS 1.3, while older devices can still access the site via TLS 1.2, minimizing configuration risk.

　　In summary, the difference between TLS 1.3 and TLS 1.2 is not just a difference in version numbers, but a conceptual upgrade. TLS 1.2 is a protocol that balances historical and contemporary considerations, flexible but complex. TLS 1.3 is a protocol geared towards the modern internet, radical but secure. For novice website owners, TLS 1.2 provides necessary compatibility, while TLS 1.3 is the strongly recommended modern choice. As long as the server and environment support it, enabling TLS 1.3 has virtually no downsides.