Last week was amazon, now its microsoft

I am a software developer. The chances of the entire internet crashing are extremely slim. There is a lot of redundancy built in.

Any company with common sense doesn't run a website or service on one machine (server). If one server goes down, the others pick up more of the load until another one starts up. Think of it like going to a fast food restaurant where 3 people are serving at the countrr with a little time to spare between customers. If one goes on break, the other two just serve more customers until they get back.

Companies will usually use at least 3 servers but often more, and they will often be spread so that a single failure will not take down the service. They might be placed on different power supplies so that a power cut doesn't take them all out, putting them in different cities, or I think the most extreme one I've heard is making sure they are on different tectonic plates for protection against earthquakes. Think of this like having two restaurants in case one of them is closed; or in the worst case, one burns down. The food can still be available via the other restaurnat. 

So with all those protections why did so much start going wrong? Human error most likely. News sites have reported DNS was the culprit in both cases, which is very suseptible to this kind of issue. DNS is like an address book or telephone directory. If you want to contact someone and know their name (or web address), you can look up the details of how to contact them in the address book. Someone has to keep the address book updated though. Most likely someone updated some records incorrectly, which meant the servers didn't know how to find each other.

Thankfully these kinds of issues tend to be rare, and no doubt Microsoft and Amazon will be looking into what went wrong, how to reduce the risk of it in future, and how to recover more quickly if it does happen. Aside from anything else, there will be significant financial losses to motivate them as a result. They're public companies so their stock will have tanked, companies pay for server time so they won't be getting paid for that, but it can also be written into some contracts they they have to pay their customers if they have significant outages.

The other point is probably that the internet is an extremely complicated system with many moving parts, with old things being removed and new things added every moment. It is probably inevitable that we will have these issues every so often.

I understand what you're saying but as individuals we also need to be prepared to be more resilient.  Web based systems go down all the time,  fortunately it's only for a few hours or days at most.   So when I go out I carry debit cards, credit cards and £100 in cash and small change.

In my travels I've come across many cash only businesses and contactless only businesses. 

For example,  in Haworth,  home of the Bronte sisters, I got caught short and the public toilets in the park were 30p contactless only payment, no option for cash.  My credit card was invaluable. 

In Llandudno the public toilets were cash only, 50p, but the doors accepted £1 coins and no cash change given, I was lucky to have small change.

Absoltely! My comment was more pointing out that these large scale outages are typically rare, and the chances of the entrie internet going down are very slim. However, these outages are also probably inevitable. It's the nature of them that when things do go wrong to the level that it causes problems, it causes lots of problems.

It makes absolute sense to keep some cash for these situations, and even split your money across banks.

Absoltely! My comment was more pointing out that these large scale outages are typically rare, and the chances of the entrie internet going down are very slim. However, these outages are also probably inevitable. It's the nature of them that when things do go wrong to the level that it causes problems, it causes lots of problems.

It makes absolute sense to keep some cash for these situations, and even split your money across banks.