Scalability Basics

Core idea

Scalability means a system can handle more work without falling apart. This usually involves distributing traffic, reducing repeated work, and removing single points of failure.

Common ideas

• Horizontal scaling adds more machines.
• Caching reduces repeated expensive work.
• Queues smooth out traffic spikes by handling work asynchronously.

more users -> more requests -> scale app layer -> protect database

Revision points

• Load balancers spread traffic across multiple servers.
• Caches speed up repeated reads.
• Databases often become the hardest component to scale well.

What to remember

Scaling is not only about speed. It is also about keeping the system stable as demand rises.