Key idea
The cloud is other people's computers, rented over the internet. You pay while you use them, get more in minutes, and hand them back when you're done, while the provider keeps the hardware running.
This path follows one trip: a person types your address into a browser, and a page comes back. Each module opens one stop on the way, marked on the strip above.
The cloud at a glance
What owning looks like
Before the cloud, putting an app online meant buying a server, finding a room with power, cooling and a fast internet line, and installing everything yourself. When a disk died at 3 a.m., it was your disk.
You also had to guess. Buy for your busiest day and most of the machine sits idle the rest of the year. Buy for a normal day and the busy one takes you offline.
What renting changes
A cloud provider runs huge buildings full of machines, called data centers, and rents them out in small pieces.
- Minutes, not months. You ask for a machine and it's running shortly after. No purchase order, no delivery.
- Pay for what runs. Billing is by the second, hour or month. Turn something off and it stops costing money.
- Scale both ways. Add more capacity for a launch, remove it the week after.
- Someone else's hardware problems. A failed disk or power supply is the provider's job to replace.
Providers group their data centers into regions, such as a city or a part of a country. You pick one close to your users, because every request has to travel there and back.
What renting doesn't change
Renting isn't free of trade-offs. A machine that runs flat out all year can cost more rented than bought. You depend on the provider staying up, and moving to another one takes work.
And your app is still yours. If it crashes, leaks a password or loses data, the provider's hardware being fine won't help. How much of the rest you hand over depends on what kind of service you rent. That's the next lesson.
Check yourself