There's nothing more annoying than recording a screencast and having alerts pop up in the corner of your screen. 

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You can turn these off, temporarily, while you share your screen. 

Here's how to do it on computers and phones:

MacOS

In the top right corner of your Mac screen, click on the Notifications Center icon:

In the TODAY section, you'll see this:

Using your scroll wheel or trackpad, pull this menu DOWN to see the hidden screen above: 

Switch DO NOT DISTURB to ON while you record. 

iOS

On an iPhone, DO NOT DISTURB looks like a Moon. Swipe up on your home screen to open your control center. Click the Moon icon to disable notifications (until 7:00 am the following morning, or until you tap the Moon icon again).

You have a lot of choice when it comes to this feature. Read more tips here. 

Windows

via:https://www.windowscentral.com/how-disable-notifications-while-presenting-windows-10

When using Windows, you can temporary hide notifications using "Focus Assist".

To turn on Focus Assist, do the following:

1. Click the Action Center button in the bottom-right corner of the screen.
2. If you don't see the Focus Assist button, click the Expand button at the bottom of Action Center.

3. Click the Focus Assist button to stop the flow of notifications while presenting to complete the task.

   

Once you finish your presentation, you'll to need turn off Focus Assist manually using the same steps mentioned above to see desktop notifications again. Please note that because there are two different modes for focus assist, you may need to click the button twice to disable it. If you choose "alarms only", then all notifications will be blocked, where as "priority only" mode allows some through that have been deemed important by windows.

Quick Tip: You can also right-click the Action Center button in the Taskbar to turn on or off Focus Assist on Windows 10.

Android 

Pull down from the top to see the quick settings bar. Find the icon of a circle with a dash in it which turns on Do Not Disturb.