SharePoint may be INSTALLED and used in three different ways.

1. SharePoint Foundation
2. SharePoint Server
3. OFFICE 365

SharePoint Foundation and SharePoint Server are SharePoint on-premises with Office 365 emerging as a third, completely cloud-hosted model for SharePoint.

1. SharePoint Foundation: SharePoint Foundation is a must-have for businesses looking for a safe, manageable web-based collaboration platform. SharePoint Foundation gives you access to the most basic collaboration functions available in SharePoint.

Key Features:

• Team websites provide access to information in a central area, allowing for effective document and task collaboration.
• Reduced resources for implementation and deployment SharePoint Foundation is a free download for Windows Server customers that significantly reduces the time and cost of setup.
• SharePoint Foundation also includes data and information MANAGEMENT and security tools for better control of your organization's critical business data.
• By extending and customizing SharePoint Foundation, you can embrace the web for collaboration.

2. SharePoint Server: SharePoint Server has a lot of capabilities that aren't available in SharePoint Foundation. It provides a more comprehensive, advanced set of capabilities that you may use in your company's solutions.

Key Features:

• Advanced Search: The search and functionality capabilities offered in the Server versions provide you with more options. They allow you to create customized Search Results pages using custom search Web Parts.
• SharePoint Server's Online Content Management feature allows you to create and publish web content for the internet.
• Enterprise Services: These services allow you to rapidly and simply create custom solutions utilizing tools from the Office product family.
• Business Connectivity Services (BCS) allows you to connect to various external data sources and show business data through Web Parts, user profiles, and SharePoint lists.
• SharePoint Server's records management capabilities are useful for managing material throughout its life cycle.

3. Office 365: Office 365 has emerged as a third, completely cloud-hosted SharePoint solution. It's a viable alternative to operating your own farm in your own Data Center.

Key Features:

• The number of users you want to add, the AMOUNT of data you need to store, and the capabilities you require are all aspects to consider when licensing SharePoint Online through Office 365.
• It's also become a terrific area to build rich apps (both SharePoint-hosted and cloud-hosted apps) and expand without having to worry about managing on-premises infrastructure.
• It doesn't have all of SharePoint Server's services and functionality, but it does have some impressive development possibilities.