Uptime defines the time your website is available for the users. If you experience technical or redirect issues down the line, downtime will kill your SEO quite fast.
Why is uptime so important?
First of all, if Google sends their bots to crawl your website, it has to be available to get checked at all. Even if search engines were able to crawl your site, but your server uptime is pretty low, you will experience bad user signals due to immediate bounces. This will worsen your page authority really quickly.
If you are doing some online marketing and sending traffic via Social Media Marketing or Search Engine Marketing (PPC) to your website, you are also basically spending money on a website/landing page, which is not available.
Some math along the way
Guess you have all heard or read about it. Web hosting providers promising 99% availability and more (which sounds a lot). But for example:
An uptime of 99% in 365 days still means that your 87.6 hours (=3.65 days) every year.
Maybe that’s not that important for you as long as you have an informational website. But as soon as you have a shop or B2C/B2B website, things like that matter. You are losing not only money but also customers. These customers probably won’t come back to check in again on you. Those customers will most likely be lost forever.
There are two solutions that I’d like to tell you about:
If you want to have the best notification system out there that I know of and use it in any professional context you should use Pingdom. Pingdom checks at least every minute whether your website is available or not. You can add deep links as well so make sure to not only check the start page of your website but also some other pages in subfolders.
In case it’s for a personal project, use Statuscake for free (it is free and will ever be free according to the publisher). They are checking in on your URL and even here you can use these deep links to monitor if all pages are unavailable or just one page for whatever reason.
Usually, I expect that all pages are either up or not. There is very rarely something in between.