It could happen at any time. Maybe an asteroid will hurtle toward Earth or a storm will cover the world in ice. A bite from a particularly angry monkey could start a viral zombie plague. The Internet could even shut off. Things could go to hell because of monsters or uncomfortably sentient robots, nuclear war or a terrorist attack. The question you should ask yourself is: What will you eat and drink when the world ends?
The people answering this question aren’t scientists, the military, or NASA (though maybe there’s a secret apocalypse science division in the government). They’re known as “preppers” and are usually everyday folks with normal jobs — teachers or bankers or candlestick makers.