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Beginner 1 minute
Horizontal vs Vertical Scaling
Vertical scaling makes one machine stronger by adding CPU, memory, or faster storage. Horizontal scaling adds more machines and spreads work across them. Vertical scaling is easy to understand but has hardware limits and a larger single failure. Horizontal scaling offers more capacity and resilience, though it requires routing, coordination, and often stateless application design.
Key idea
Vertical means scale up. Horizontal means scale out.
See it in one picture
Follow the arrowsScale upBigger server
Make one machine stronger
Scale outMore servers
Add more machines
Real-world example
A small database may first move to a larger instance. A busy web tier usually adds more identical servers behind a load balancer so traffic can keep flowing when one server is unavailable.
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