The following was prompted by threads on numerous mailing lists regarding Windows 10 toasts/notifications (they are really the same thing). I hope it can serve as a handy reference in answer all sorts of questions you may have about them (a copy of the below FAQ was sent to a Windows 10 list).
Q. What are toasts?
Another name for notifications. Basically, when an application (regardless of source; see below) presents a notification, Windows 10 will present a message on the right-hand side of the screen that’ll go away after a short while.
Q. Which apps or situations can send notifications?
Any app capable of sending notifications will ask Windows to present notifications. These include installed apps, web applications and certain websites, and Windows itself.
Q. How do I interact with notifications when they appear?
Depending on which Windows 10 release you are using (you can check this by opening About Windows/Winver):
Note: Version 1809 and later reserves Windows+V for clipboard history (a separate topic).
Q. What if I miss these notifications?
All notifications will eventually end up on Action Center (Windows+A).
Q. While using Skype in the background, I get a call. How can I answer calls?
Incoming calls are notifications. Therefore you can activate these notifications and press Enter to accept or use options to decline the call.
Q. I’m using a recent version of Chrome and somehow I get notifications from nowhere. What should I do?
Web applications, or more specifically, apps for websites can send notifications through a web browser. Just like any notification, you can activate the notification and deal with it.
Although each web browser differs in terms of stopping these notifications, the general steps involve opening the web browser and asking it to stop sending notifications.
Q. How come some notifications have additional controls, not just a button to dismiss it?
These are called actionable notifications. If an app wants you to take a follow-up action (such as answering a call on Skype), the notification will feature additional controls such as an edit field to send a reply, answering a call, opening a specific app, or taking additional actions.
Q. I don’t want to see notifications from certain apps. How can I configure this?
To configure this, open Settings (Windows+I)/System/notifications and Actions. Scroll (press Tab) through this screen, and from “get notifications from these senders” section, go through each app and toggle the notifications on or off.
Q. What if I want to tell apps I don’t want to see notifications while I’m busy with something?
This is done by setting up focus assist (formerly quiet hours). As of Version 1903 (May 2019 Update), focus assist can be used to silence notifications while you are in a full-screen application or playing games, as well as asking Windows to send notifications from a priority list or alarms.
At least the above FAQ should cover majority of cases. Please let us know if other scenarios should be added.