SharePoint is a web-based collaborative platform that integrates with Microsoft Office. Its primary features include document management, web content management, workflow automation, search functionality, and business intelligence integration.

SharePoint's architecture consists of multiple layers including the Web Front End (WFE) servers, Application servers, Database servers, and the Client Object Model. The WFE handles web page requests, the Application layer runs service applications like search, and databases store the data.

SharePoint Online is a cloud-based service provided by Microsoft as part of Office 365. It eliminates the need for an internal IT team to manage servers. SharePoint On-Premises requires an in-house infrastructure and offers more control over data but can be costlier to maintain.

SharePoint Lists are used to store data in rows and columns similar to a database or Excel spreadsheet, whereas Libraries are specialized lists for storing documents. Both provide features like versioning, metadata, and permissions.

Permissions in SharePoint are managed through groups and permission levels such as 'Read,' 'Contribute,' 'Edit,' and 'Full Control.' Permissions can be set at the site, list, library, folder, or item level, and inheritance can be broken to granularly manage access.

SharePoint Workflows automate business processes by managing the movement of documents and items through specific sequences of actions or tasks. They improve efficiency, ensure consistency, and provide transparency in process management.