Tag
Caching
Learn how browsers and intermediaries store, validate, and reuse HTTP responses with cache directives, validators, and conditional requests. This curated hub brings together 16 related resources.
301 vs 302 Redirects
Understand the difference between 301 Moved Permanently and 302 Found redirects. Learn when to use each, how browsers cache them, and their SEO implications.
304 Not Modified
Cached response is still valid. Learn how 304 Not Modified improves performance through conditional requests and caching.
304 Not Modified vs 200 OK
Understand when servers return 304 Not Modified instead of 200 OK. Learn how conditional requests, ETags, and Last-Modified headers enable efficient HTTP caching.
Age Header
Learn how the Age header indicates how long a response has been cached in seconds. Understand cache freshness calculations and CDN behavior.
Cache-Control Header: Complete HTTP Caching Guide
Master the Cache-Control header. Learn how to control browser and CDN caching with max-age, no-cache, no-store, and other directives.
Cache-Control: no-cache vs no-store
Compare the no-cache and no-store Cache-Control response directives and choose the correct policy for sensitive or frequently changing responses.
ETag
Learn how the ETag header provides a unique identifier for resource versions, enabling efficient cache validation and conditional requests to reduce bandwidth.
Expires Header
Learn how the Expires header specifies when cached responses become stale. Understand date formats and when to use Expires vs Cache-Control for caching.
GET vs POST
Understand the fundamental differences between GET and POST HTTP methods. Learn about safety, idempotency, caching, request bodies, and when to use each.
HTTP Headers and Caching: A Practical Guide
Master HTTP caching with Cache-Control, ETag, Last-Modified, and conditional request headers. Learn how to optimize performance with proper cache strategies.
If-Modified-Since Header
Learn how the If-Modified-Since header requests resources only if modified since a specific date. Reduce bandwidth with efficient conditional caching.
If-None-Match Header
Learn how the If-None-Match header makes conditional requests using ETags. Avoid downloading unchanged resources and reduce bandwidth with cache validation.
If-Unmodified-Since Header
Learn how the If-Unmodified-Since header makes requests conditional on resources not being modified. Prevent conflicts in concurrent update scenarios.
Last-Modified
Learn how the Last-Modified header indicates when a resource was last changed. Enable efficient cache validation with If-Modified-Since conditional requests.
Vary
Learn how the Vary header specifies which request headers affect the response. Essential for proper cache differentiation and content negotiation.
Warning Header
Learn about the deprecated Warning header that provided additional status information about message transformations. Understand why it was removed from HTTP.