HTTP is the protocol browsers and servers use to exchange requests and responses. HTTPS is the same protocol wrapped in encryption. HTTP/2 and HTTP/3 are newer versions of the transport layer underneath both, built to move data faster over the same connection. You need HTTPS for security and SEO, and modern hosting typically handles HTTP/2 or HTTP/3 automatically, no configuration required.
If you're troubleshooting a specific error code rather than trying to understand the protocol itself, see HTTP status codes explained.
HTTP: the base protocol
HTTP (Hypertext Transfer Protocol) defines how a client, usually a browser, asks a server for a resource and how the server replies. A request has a method (GET, POST, PUT, DELETE, and others), a URL, headers, and sometimes a body. A response has a status code, headers, and usually a body: HTML, JSON, an image, whatever was asked for.
HTTP itself is plain text on the wire. Anyone sitting between the browser and the server, a coffee shop Wi-Fi router, an ISP, a compromised network device, can read every request and response, including form submissions and login credentials. That's the problem HTTPS solves.
HTTPS: HTTP over TLS
HTTPS is HTTP sent through a TLS (Transport Layer Security) encrypted connection. Before any HTTP data moves, the browser and server perform a TLS handshake: they agree on encryption methods and the server proves its identity with an SSL/TLS certificate signed by a trusted certificate authority. Once that handshake completes, everything sent over the connection is encrypted, so an eavesdropper sees scrambled bytes instead of readable data.
This matters for three reasons. First, security: passwords, payment details, and session cookies stay private in transit. Second, trust: browsers mark plain HTTP sites as "Not secure" and will refuse to run certain features (camera, geolocation, service workers) without HTTPS. Third, SEO: search engines treat HTTPS as a ranking signal and will not show the padlock without it.
On Flashcloud, every hosted domain gets a free Let's Encrypt SSL certificate, issued automatically within about 5 minutes of your domain pointing to us, and renewed automatically before it expires. You don't request it or install it yourself.
HTTP/2: multiplexing over one connection
HTTP/1.1 has a bottleneck: a browser can only run a limited number of requests at a time per connection to a domain, so loading a page with dozens of images, scripts, and stylesheets means either queuing requests or opening several connections, each with its own overhead.
HTTP/2 fixes this with multiplexing: many requests and responses travel over a single TCP connection at the same time, interleaved as binary frames instead of queued as plain text. It also compresses headers (which repeat a lot between requests) and lets the server push resources it knows the browser will need. The practical effect is pages with many small assets load faster, with no code changes required on your end.
HTTP/3: built on QUIC instead of TCP
HTTP/2 still rides on TCP, which has its own weakness: if a single packet is lost, TCP blocks the entire connection until that packet is retransmitted, even for unrelated requests. This is called head-of-line blocking, and it's worse on unstable connections like mobile networks.
HTTP/3 replaces TCP with QUIC, a transport protocol built on UDP. QUIC handles each stream independently, so a lost packet only stalls the one request it belongs to, not the whole connection. QUIC also folds the TLS handshake into its own connection setup, which shaves a round trip off the time to first byte compared to TCP plus TLS. The result is a faster, more resilient connection, especially on unstable Wi-Fi or cellular data.
What this means for your site
You don't choose HTTP/2 or HTTP/3 the way you choose a WordPress theme. They're negotiated automatically between the browser and the server's web server software, and both sides fall back gracefully to an older version if either doesn't support the newer one. Flashcloud runs LiteSpeed Web Server on shared and WordPress plans, which supports HTTP/2, alongside LSCache for page caching. Combined with the automatic SSL mentioned above, a site on Flashcloud gets HTTPS and HTTP/2 without any manual setup.
The one thing worth checking on your own site is mixed content: if your HTML references any resources (images, scripts, stylesheets) over plain http:// instead of https://, browsers will block or warn on them even though your main page is secure. Search your site's HTML or database for hardcoded http:// links pointing at your own domain and switch them to https:// or protocol-relative paths.
When to contact support
If your domain shows "Not secure" more than a few minutes after DNS points to us, or a certificate error persists, open a ticket from Support in the portal. A real person will look into it.