The classic way to have a drop-down list in html is the select tag.
However there are two main problems/inconvenient. The select tag will only allow to select one item and you cannot type for a not included option or just to filter the list options. Also sometimes just have all the input fields under the same tag name <input> is just niter.
An other way is the <datalist>, that for some reason I learned about it lately (sad).
The classic example:
<input list="hashes"> <datalist id="hashes"> <option value="sha1"> <option value="sha256"> <option value="sha512"> </datalist>