What is MS Outlook?

Microsoft Outlook is a personal information manager from Microsoft. It is widely used as an e-mail application. However, it also provide other services like calendar, task manager, contact manager, note taking, journal, and web browsing.

Microsoft Outlook is used as a stand-alone application, or with Microsoft Exchange Server and Microsoft SharePoint Server for multiple users in an organization, such as shared mailboxes and calendars, Exchange public folders, SharePoint lists, and meeting schedules. Microsoft has also released mobile applications for most mobile platforms, including iOS and Android. It also allows developers to create their own custom software that works with Outlook and Office components using Microsoft Visual Studio. It allows windows mobile devices to synchronize their Outlook data to Outlook Mobile.

(source: Wikipedia)