This recent BBC feature on “black sky events” — a total grid-down in a large area, like a city or even a country — is worth reading in full if you want to better understand what living through a large-scale blackout looks like.

While the term “black sky” events illustrates perhaps the most visible impact of widespread power failures, it fails to convey the scale of the impact these can have. In our modern world, almost everything, from our financial systems to our communication networks, are utterly reliant upon electricity. Other critical infrastructure like water supplies and our sewer systems rely upon electric powered pumps to keep them running. With no power, fuel pumps at petrol stations stop working, road signs, traffic lights and train systems go dead. Transport networks grind to a halt. Our complex food supply chains quickly fall apart without computers to coordinate where produce needs to be, or the fuel to transport it or refrigeration to preserve it. Air conditioning, gas boilers and heating systems also rely upon electricity to work.

The piece goes on to detail the effects of regional grid-down events in Venezuela, Argentina, Uruguay and Paraguay, and some of the larger recent outages in North America. There is also some discussion of European blackouts, including a 2003 event where a pair of fallen trees in just the right two locations at the right time briefly cut the power [PDF] to the entire country of Italy.

Hospitals are some of the hardest hit, though most have backup generators with at least five days worth of fuel. Also affected are fuel and transport infrastructure, financial systems, and everything else that makes modern life go — the piece does a good job with the kinds of cascade effects we covered in our EMP guide.

If you’re worried about a blackout and looking to get prepared, start with our post on How to get ready for a 3-day blackout for under $100. That post has everything you need to cover the basics on a budget, from power to food and water.

You’ll also want to take a look at the following power-specific guides: