Microsoft SharePoint (Online) is a collection of (cloud- and) web-based technologies that makes it easy to store, share and manage digital information within an organization.
Organizations use SharePoint to create websites. You can use it as a secure place to store, organize, share, and access information from almost any device. All you need is a web browser, such as Internet Explorer, Chrome, or Firefox. SharePoint products and technologies include the following:
SharePoint Online: A cloud-based service, hosted by Microsoft, for businesses of all sizes. Instead of installing and deploying SharePoint Server on-premises, any business can subscribe to an Office 365 plan or to the standalone SharePoint Online service. Your employees can create sites to share documents and information with colleagues, partners, and customer.
SharePoint Server: Organizations can deploy and manage SharePoint Server on-premises. It includes all the features of SharePoint Foundation. And it offers additional features and capabilities, such as Enterprise Content Management, business intelligence, enterprise search, personal sites and Newsfeed.
SharePoint Foundation: No longer available separately for the SharePoint 2016 release, SharePoint Foundation was the underlying technology for all SharePoint sites. SharePoint Foundation (formerly Windows SharePoint Services) is free for on-premises deployment. You can use SharePoint Foundation to create many types of sites where you can collaborate on webpages, documents, lists, calendars, and data.