Sometimes even Salesforce' server clusters struggle. Then you might encounter a downtime or a service degradation. Should you want to be informed about these occurrences related to your system, you can either review messages on https://status.salesforce.com/ or even subscribe to get instant updates about potential issues or maintenance work being conducted.

Subscribing to alerts and service notifications is easy! 

After you opened the Salesforce Status Page, you first will need to connect an email address to the page, so with other words, create an account.

The fastest way to achieve this is to go to the sign in/sign up page: https://status.salesforce.com/login

If you haven't setup an email yet, it will send you a link which will create an account for you where you can manage your subscriptions:

If you use the same email again, it will also send you a link that takes you to manage your subscriptions:

To create a new subscription, simply click on "Create New" and decide if you want "General Messages" or the instance you want to be informed about. You can find your instance abbreviation in Setup>Company Information (also for Sandboxes):

And which services you are interested in being informed about:

Repeat this for all instances you are interested in. Normally your production and perhaps a sandbox instance will suffice. Potentially, you may be interested in "General Messages", too. 

You can unsubscribe at any time and manage your subscriptions as needed.