As with [Fragments](10-fragments.md), Extensions can be used to make your Compose file more efficient and easier to maintain. Extensions can also be used with [anchors and aliases](10-fragments.md).

Use the prefix `x-` as a top-level element to modularize configurations that you want to reuse. 
Compose ignores any fields that start with `x-`, this is the sole exception where Compose silently ignores unrecognized fields.