Office.context

This provides access to some of the Common API properties.
This represents the runtime environment of the add-in and provides access to key objects of the API.
The current context exists as a property of Office.

Office.context

auth	Provides information and access to the signed-in user.
commerceAllowed	True, if the current platform allows the add-in to display a UI for selling or upgrading; otherwise returns False.
contentLanguage	Gets the locale (language) specified by the user for editing the document or item.
diagnostics	Gets information about the environment in which the add-in is running.
displayLanguage	Gets the locale (language) specified by the user for the UI of the Office host application.
document	Gets an object that represents the document the content or task pane add-in is interacting with.
host	Contains the Office application host in which the add-in is running. Important: In Outlook, this property is available from requirement set 1.5. For all Mailbox requirement sets, you can use the Office.context.diagnostics property to get the host.
license	Gets the license information for the user's Office installation.
mailbox	Provides access to the Microsoft Outlook add-in object model.
officeTheme	Provides access to the properties for Office theme colors.
platform	Provides the platform on which the add-in is running. Important: In Outlook, this property is available from requirement set 1.5. For all Mailbox requirement sets, you can use the Office.context.diagnostics property to get the platform.
requirements	Provides a method for determining what requirement sets are supported on the current host and platform.
roamingSettings	Gets an object that represents the custom settings or state of a mail add-in saved to a user's mailbox. The RoamingSettings object lets you store and access data for a mail add-in that is stored in a user's mailbox, so it's available to that add-in when it is running from any host client application used to access that mailbox.
touchEnabled	Specifies whether the platform and device allows touch interaction. True if the add-in is running on a touch device, such as an iPad; false otherwise.
ui	Provides objects and methods that you can use to create and manipulate UI components, such as dialog boxes.