On a Mac, your notifications live behind the clock
On a Mac there is no notification tray in the corner. Missed alerts collect behind the clock, and the real win is turning the noisy ones off.
When something pinged on Windows and I missed it, I went hunting in the tray at the bottom right. On a Mac there is nothing down there. The first time I missed an alert, I had no idea where it went.
It went behind the clock. Click the date and time in the top-right corner and every missed notification is waiting, stacked and ready. That panel is called Notification Center. You can also open it by swiping left with two fingers from the right edge of the trackpad, and close it by clicking the desktop or swiping back.
That is the part people look for. This is the part that actually matters.
The defaults are chatty. Turn them down.
Out of the box, a lot of apps assume you want to hear from them. Badges, banners, the works. You do not have to live with it.
The fastest fix is to do it the moment an app annoys you. When its notification shows up, click the small arrow next to the app name, then More, and you can mute it or turn it off without digging through settings. Do that two or three times in your first week and the noise drops to almost nothing.
When you need real quiet, turn on a Focus like Do Not Disturb. A Focus silences everything, or lets through only the people and apps you choose. It is the difference between muting alerts one by one and flipping a single switch before you sit down to work.
Dealing with what's already there
Open Notification Center and a few things are worth knowing.
Notifications group by app into stacks. Click the top one to open the whole stack, and Show less to close it again. You can act without opening the app: Reply on a mail, Snooze on a calendar alert. If an action has an arrow, click it for more options. To clear one, click its close button. To clear a whole stack at once, hold the pointer over the top notification's clear button and choose Clear All.
The widgets
The same panel holds widgets, the small glanceable panels for your calendar, the weather, reminders, and more. Click one to open its app. To change a widget, Control-click it and pick a size, or hold Option and click the minus to remove it.
Mac notifications are easy to use and easy to ignore. Spend five minutes shutting off the ones you do not need, and the clock becomes a place you check when you want to, not a stream you have to fight.
For the full details, see Apple's guide, Use Notification Center on Mac.
Frequently asked questions
Where are notifications on a Mac?
Behind the clock. Click the date and time in the top-right corner to open Notification Center, where every missed alert is stacked and waiting. You can also swipe left with two fingers from the right edge of the trackpad.
How do I turn off notifications for an app?
When a notification appears, click the small arrow next to the app name, then More, and mute or turn it off. Doing this the moment an app annoys you is the fastest way to quiet things down.
What is the Mac equivalent of Focus Assist or quiet hours?
A Focus, like Do Not Disturb. Turn it on to silence everything, or to let through only the people and apps you choose.