How HTTPS works
HTTPS is the ordinary web protocol with a layer of encryption wrapped around it. Before any page content moves, the browser and the server agree on a shared secret using the site’s certificate. After that, everything — the address requested, the form fields submitted, the response returned — travels in a form only those two can read.
It protects three things at once. Privacy, so an observer cannot read what was sent. Integrity, so nothing can be altered on the way. And identity, so the browser can confirm it is talking to the domain shown in the address bar rather than to something impersonating it. The first is the one people expect; the second is why an internet provider or a public network cannot inject advertising or scripts into your pages.
Why HTTPS matters
Browsers made the decision for everyone. Pages served over plain HTTP are marked as not secure, and any page carrying a password or a card field gets a stronger warning still. Visitors do not need to understand the protocol to act on the label.
A number of things also simply do not work without it. Modern browser features, payment integrations and some tracking and consent tools require a secure context. Search engines have long treated it as expected rather than exceptional, so adding it removes a disadvantage more than it creates an advantage.
The commercial effect shows up on forms. People are noticeably more reluctant to type a phone number or an address into a page the browser has flagged as unsafe.
Where HTTPS goes wrong
Half-finished migrations cause most of the trouble. Pages load securely, but a stylesheet, an image or a script is still requested insecurely, which produces mixed content. Browsers block the insecure asset and layouts break in ways that are easy to miss when you only test one page.
The other half is addressing. If both the insecure and secure versions of a page respond, search engines see duplicates, and a canonical tag still pointing at the old address quietly undoes the move. Internal links written as absolute insecure addresses do the same thing.
Redirect chains are the third problem: insecure to secure, then to the www version, then to a trailing slash, each hop costing time on every single request.
What to do about it
Redirect every insecure address to its exact secure equivalent with a permanent redirect, in a single hop, and never to the homepage. Update internal links, canonical tags, the sitemap, and any hard-coded addresses sitting in the theme or the database.
Then verify rather than assume. Load your key templates and watch for blocked requests, confirm the secure property is the one reporting in Search Console, and check that redirects resolve in one step. Once everything is stable, consider HSTS so browsers request the secure address from the start — but only when you are certain the whole site works over it, because it is deliberately difficult to reverse. This clean-up sits squarely within technical SEO.