- Last Updated: - [[2021-01-21]] - Cache headers are parameters and values that are part of standard HTTP specification and determine if, when, and how resources may be saved locally by a client. - `Pragma: no-cache` - Pragma headers are for optional behavior, so this directive may be ignored. This shouldn't be used to enforce caching. - `Cache-Control` - "Cache-Control Cache-Control headers were introduced in HTTP/1.1 to specify directives that must be followed by all caching implementations in the request/response chain. The common Cache-Control directives you will come across are: public private no-cache no-store no-transform must-revalidate proxy-revalidate max-age s-maxage " - `Expires` - This header encourages a time-based caching model, where content is saved until they are considered "stale" (old). `Cache-Control` can still override these. - `Last Modified` - Takes a date and time as a value. This date indicates when the content being fetched was last updated. - `ETag` - Identifies the resource version with a unique tag. This allows the browser to request the resource if it does not have the latest version. -