The recommended way to use OpenLayers is to work with the ol package. You can install the latest with npm:

npm install ol

If you want to try out OpenLayers without downloading anything (not recommended for production), include the following in the head of your html page:

<script src="https://cdn.rawgit.com/openlayers/openlayers.github.io/master/en/v5.1.3/build/ol.js"></script>
<link rel="stylesheet" href="https://cdn.rawgit.com/openlayers/openlayers.github.io/master/en/v5.1.3/css/ol.css">

Archive	Description
v5.1.3-dist.zip	Includes a full build of the library (ol.js), a source map (ol.js.map), and library CSS (ol.css with source map ol.css.map).
v5.1.3.zip	Includes all of the above plus examples, API docs, and sources.

See the v5.1.3 release page for a changelog and any special upgrade notes.

For archives of previous releases, see the complete list of releases.