Header cache control in WordPress refers to the management of the Cache-Control HTTP header sent by your WordPress site to a user's browser. This header is a crucial tool for controlling the caching of requests and responses in an end-user's browser. It dictates how long browser should store pages, images, and other assets before checking for updates.
Essentially, when a browser receives a response from your WordPress site, the Cache-Control header tells it whether it can save a copy of that content and, if so, for how long. This helps improve site speed by allowing returning visitors to load cached versions of pages and assets directly from their browser's local storage instead of downloading them again from the server.
Understanding the Cache-Control Header
The Cache-Control header is part of the standard HTTP protocol and contains one or more "directives" that define caching policies.
Common directives include:
max-age=seconds: Specifies the maximum amount of time (in seconds) a resource is considered fresh.no-cache: Requires revalidation with the server before using a cached copy. It doesn't mean "don't cache", but rather "always check if the cached version is still valid".no-store: Instructs the browser not to cache any part of the response.public: Indicates that the response may be cached by any cache, including shared caches (like proxies).private: Indicates that the response is intended for a single user and should not be stored by shared caches.must-revalidate: Tells the browser that once the resource becomes stale (aftermax-ageexpires), it must revalidate with the server before using the cached copy.
Cache-Control in WordPress Hosting Environments
While WordPress itself doesn't set aggressive browser caching headers by default for every resource, hosting providers, especially managed WordPress hosts or platforms like VIP, often implement server-level caching and configure default Cache-Control headers.
According to the reference provided:
The cache-control HTTP header provides an instructional value for controlling the caching of requests and responses in an end-user's browser. Default cache-control response header values set by VIP's page cache: cache-control: max-age=300, must-revalidate (5 minutes) for most responses with an HTTP Status Code of 200 .
This means for typical successful page loads (HTTP Status Code 200), the VIP platform sets the following header by default:
| Header Name | Value | Meaning |
|---|---|---|
Cache-Control |
max-age=300, must-revalidate |
Cache the response for 300 seconds (5 minutes) and revalidate after that. |
This configuration tells the user's browser to cache the page content for 5 minutes. After 5 minutes, if the user revisits the page, the browser must check with the server (must-revalidate) to see if the content has changed before displaying the cached version. This balances performance benefits with ensuring content freshness.
Benefits for WordPress Sites
Implementing proper header cache control for your WordPress site helps in several ways:
- Faster Load Times: Reduces the need for browsers to re-download static assets and page content.
- Reduced Server Load: Fewer requests hit your server for cached resources.
- Improved User Experience: Visitors have a snappier browsing experience.
- Lower Bandwidth Usage: Saves bandwidth for both the server and the user.
Managing Cache-Control can be done through server configurations (like .htaccess for Apache or nginx configs), caching plugins, or is handled automatically by robust hosting environments like WordPress VIP.
