AMP pages can now more closely mirror the behavior of regular HTML pages with autocomplete for search and forms.
An autocomplete-enabled input field suggests completed results corresponding to what the user is typing.
As you likely know from this being a common feature in regular pages, it can greatly speed up the time it takes to complete a task.
AMP-autocomplete can be used to power on-site search experiences, or in forms to help ensure inputs yield more predictable results.
When a user types into an input field with amp-autocomplete, relevant suggestions will automatically appear below the input field.
This feature can also be used to generate a list of suggestions for a particular input field.
For example, a search bar on an e-commerce site can automatically suggest the most popular products with amp-autocomplete.
Data can either be fetched from a JSON endpoint or locally from amp-state.
For more on the technicalities of how this feature works and how to set it up, see the official documentation here.