Cache

What is cache?

A cache is temporary storage that keeps copies of data, pages, or files so a later request can be answered from the copy instead of re-fetching or regenerating the content. That saves both time and load. An online store usually has several cache layers stacked together: the browser cache on the visitor’s device, a CDN or edge cache close to the user, and server-side caching of dynamic content.

Why does cache matter?

Speed affects both conversion and rankings, and caching is one of the most effective ways to cut response time. When static files are served from a CDN instead of from the origin server every time, latency drops sharply. The trade-off is that a cache serves a snapshot in time: a cached page can briefly show outdated prices or stock levels until the cache expires or is invalidated.

Common use cases

• Images and assets – product images, CSS, and JavaScript are served from the CDN edge and reused across page views.
• Browser caching is controlled by HTTP headers such as Cache-Control and ETag, which decide how long files may be reused.
• “My theme change isn’t showing” – old CSS/JS stays in cache until the file gets a new version.
• Campaign spikes where caching offloads the server when many visitors hit the same pages at once.

Shopify perspective

Shopify is a fully hosted platform, so server-side caching and TTLs are managed by Shopify — you cannot set them freely as you would on a self-hosted server. Static assets are served automatically from Shopify’s built-in CDN. When you use the asset_url filter in your theme, Shopify appends a version fingerprint to the file URL, so a new deploy automatically busts both the CDN and browser cache. It’s worth optimizing your images to WebP before they hit the cache.