Web hosting and WordPress glossary

A 301 redirect tells browsers and search engines that a page has moved to a new address for good. Visitors are sent to the new URL automatically and Google carries most of the old page’s signals over to it. It is essential after changing your URL structure or domain name, or moving to HTTPS.

Also known as: 301 redirects, permanent redirect

A CDN (Content Delivery Network) is a network of geographically spread servers that keep a copy of your site’s files: images, CSS, JavaScript and sometimes whole pages. Each visitor is served by the nearest point of presence, which cuts latency and takes load off the origin server during traffic spikes.

Also known as: Content Delivery Network, content delivery network

CLS (Cumulative Layout Shift) measures the visual stability of a page: it adds up unexpected content shifts during the visit, caused for instance by an image without dimensions, a web font or a banner injected above the text. Google rates a score below 0.1 as good.

Also known as: Cumulative Layout Shift

Core Web Vitals are three metrics defined by Google to measure what real visitors experience: LCP for loading, INP for responsiveness and CLS for visual stability. They are computed from real Chrome user visits (the CrUX report) and are part of the page experience signals Google Search takes into account.

Gzip or Brotli compression shrinks text files (HTML, CSS, JavaScript, SVG) before they are sent to the browser, which unpacks them instantly. Brotli, designed by Google, usually compresses better than Gzip at a similar speed. It is switched on at server level and needs no change to the site itself.

Also known as: Brotli, Gzip, Gzip compression, Brotli compression

HTTP/2 is the second major version of the HTTP protocol, published in 2015 (RFC 7540) and revised in 2022 (RFC 9113). It runs many requests in parallel over a single connection, compresses headers and lets resources be prioritised. Browsers only use it over HTTPS. HTTP/3 is its successor.

HTTP/3 is the third major version of the HTTP protocol, standardised by the IETF in 2022 (RFC 9114). It runs over QUIC instead of TCP: secure connections open faster and a lost packet no longer holds up the other requests, which helps on mobile networks. LiteSpeed servers support it natively.

INP (Interaction to Next Paint) measures how responsive a page is: the delay between an interaction (click, tap, key press) and the visual update it triggers, across the whole visit. It replaced FID among the Core Web Vitals in March 2024. Google rates it good under 200 milliseconds.

Also known as: Interaction to Next Paint

Lazy loading means downloading images, videos or iframes only when they get close to the visible part of the screen. WordPress has added the loading="lazy" attribute to most images automatically since version 5.5. The main image at the top of the page, however, should never be lazy-loaded.

Also known as: lazy load, lazy-load

LCP (Largest Contentful Paint) measures how long it takes to render the largest visible element of the page, often the hero image or the main heading. Google rates it good under 2.5 seconds. A fast server, a page cache, optimised images and preloading the main image all improve it.

Also known as: Largest Contentful Paint

LSCache is the page cache built into the LiteSpeed server. Pages that have already been generated are served straight by the web server, without running PHP or querying the database. On WordPress, the free LiteSpeed Cache plugin drives it: automatic purge on every change, WooCommerce cart exclusions and an optional separate mobile cache.

Also known as: LiteSpeed Cache

An object cache keeps the results of WordPress database queries in memory so they can be reused from one page to the next. It relies on Redis, Memcached or LSMCD and mostly speeds up pages that cannot be page-cached: the cart, the customer area and the dashboard. Hosterwise provides a Redis object cache on every plan.

Also known as: object caching, Redis, Memcached, LSMCD

OPcache is a PHP extension that keeps already compiled PHP code (bytecode) in memory. Without it, every request would read and compile the files of WordPress and its plugins all over again. Bundled with PHP since version 5.5, it noticeably cuts page execution time and CPU load.

Also known as: Zend OPcache

A page cache stores the complete HTML of a page after it is first generated, then sends it as-is to the next visitors without running PHP or querying the database. It is the single most effective speed-up for WordPress. It can be handled by the web server, like LSCache on LiteSpeed, or by a plugin.

Also known as: page caching, full-page cache

A permalink is the permanent address of a post or page. WordPress lets you pick its structure under Settings → Permalinks; the “Post name” structure (/%postname%/) gives short, readable URLs. Changing the structure of an existing site means redirecting the old addresses with 301s.

Also known as: permalinks

A point of presence (PoP) is a physical location where a CDN runs servers, as close as possible to the internet users of a region. Visitors are routed to the nearest PoP, which serves them the cached copy of the page: less distance, so less latency. The QUIC.cloud network had 78 PoPs on 12 October 2026.

Also known as: PoP, points of presence

QUIC is a transport protocol first designed by Google and standardised by the IETF in 2021 (RFC 9000). It runs over UDP, builds in TLS 1.3 encryption and carries each data stream independently of the others. It is the foundation of HTTP/3 and mostly improves mobile or unstable connections.

QUIC.cloud is the CDN run by LiteSpeed Technologies. Placed as a reverse proxy in front of the server, it caches WordPress pages and static files in its points of presence (78 on 12 October 2026), purges them through the LiteSpeed Cache plugin and speaks HTTP/3 end to end. At Hosterwise it serves every site, on every plan.

A reverse proxy is a server placed in front of a site’s origin server: it receives visitors’ requests, answers them itself when it holds an up-to-date copy of the page and passes the rest on to the origin. It is used for caching, load balancing and traffic filtering. A CDN is a reverse proxy spread across the world.

Also known as: reverse-proxy

A staging site is a private copy of your website where you can test an update, a new plugin or a theme change without any risk to the live site. Once validated, the changes are pushed to production. It is the best protection against an update that breaks a site.

Also known as: staging, staging environment

TTFB (Time To First Byte) measures the time between the browser sending a request and receiving the first byte of the response. It adds up DNS lookup, connection, TLS negotiation and page generation on the server. Google rates it good under 0.8 seconds, and a server-side cache such as LSCache cuts it sharply.

Also known as: Time To First Byte, time to first byte, server response time

WP-Cron is the WordPress task scheduler: it publishes scheduled posts, checks for updates, sends e-mails and runs plugin jobs. It does not run continuously but fires when people visit the site. On a low-traffic site it is better to disable it and trigger it with a real server cron job.

Also known as: WP Cron, WordPress cron, wp-cron.php