HTTP vs HTTPS: what's the difference? HTTP 和 HTTPS，
差在哪？

No tech background needed. This page explains it in about three minutes. 不需要任何网络基础。这一页大约 3 分钟讲明白。

明信片 · HTTP postcard · HTTP 密封信 · HTTPS sealed · HTTPS
The same message mailed two ways — the only difference is who can read it en route. 同一句话，两种寄法——差别只有路上谁能看见。

What are these two? 这俩是什么？

HTTPHTTP the mail rules of the web — sent exactly as written 给网页送信的一套规矩：写什么，路上就是什么
HTTPSHTTPS the same rules, one extra step: sealed before it travels 同一套规矩，多一道工序：内容先封起来，再上路

HTTP and HTTPS are the same delivery rules, with one difference: whether the content is sealed. HTTP 和 HTTPS 是同一套送信规矩，差别只有一件事：内容封不封。

It's like…就像……

Write on a postcard and every pair of hands can read it. Seal it in an envelope and only the receiver can open it. 在明信片背面写话，经手的人都能看到。装进密封信封，就只有收件人拆得开。

寄信那边 in the mail 网页这边 on the web 明信片 ↔ 裸着走 postcard ↔ travels bare 密封信 ↔ 封着走 sealed ↔ travels sealed
The pairing is one-to-one: a postcard is a page travelling bare; a sealed letter, one travelling sealed. 对应是一对一的：明信片就是裸着走的网页，密封信就是封起来的。

What's the same? 它们哪里一样？

Same road, same mailing steps, same delivered page — the address differs by one letter: s. 路一样，寄的步骤一样，送到的页面也一样——网址只差一个字母 s。

同一条路 the same road 你这边 your side 网站那头 the site's end
Speed is nearly identical too: sealing costs one extra round trip on the first connection. Light in fibre covers about 200,000 km a second; a 2,000 km round trip is about 0.02s. That is under a tenth of a 0.3s blink. 速度也几乎一样：密封只在第一次连接多一个来回。光在光缆里每秒跑约 20 万公里；2000 公里外一个来回约 0.02 秒。这不到一次眨眼 0.3 秒的十分之一。

Where's the difference? 差别在哪儿？

The difference is all on the road: HTTP travels bare and readable; HTTPS travels sealed. 差别全在路上：HTTP 的内容裸着走，经手的都能看；HTTPS 封着走，只能看到乱码。

HTTP HTTPS 路上，能不能被看到？ can it be read en route? 半路，能不能被改？ can it be changed en route?
No reading, no rewriting: a broken seal cannot be resealed, so the receiver spots tampering at once. 看不成，也改不成：拆了封就合不回去，收件人一眼看出动过。

How do you tell which one you're on? 怎么分辨你在用哪种？

证书 certificatecertificate the site's ID card — proof you reached the real site, checked by the browser for you 网站的身份证：证明「你连的真是这个网站」，浏览器替你查验

Check the address bar: a padlock means HTTPS, and clicking it shows the site's certificate. 看地址栏：有锁的就是 HTTPS，点开锁还能看到它的证书。

点开锁，就能看到证书 click the lock → the certificate
The padlock in the address bar is the seal itself; click it to see the site's certificate. 地址栏的锁就是那道封条：点开它，能看到这个网站的证书。