Microsoft SharePoint Explained

Microsoft SharePoint is a private intranet site, a data repository, a smart website, a built-in content management system, a development platform, an extranet site, a collection of websites, best-in-class portal software, a document management system, a project management system, a workflow designer, and more. You can collaborate, communicate, gather decision-making reports and data from multiple resources and publish those online, make visually presentable reports, create and view intuitive and real-time dashboards, do customizations, import theme templates, and do more with your SharePoint site.

Organisations use SharePoint to create websites. You can use it as a secure place to store, organize, share, and access information from any device.

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 customers.