How to scale a web application to a million users in 10 steps

How to scale a web application to a million users in 10 steps

1- Vertically scale your server which means use a faster computer.
2- Put your database to another server, this will relieve your application server.
3- Add a load balancer and more back end servers (or basically horizontally scale)
4- Don’t forget to add a firewall which will protect you from various attacks
5- Move expensive calculations to front end like rendering web pages. Use a content deliver network
6-Add read only replicas for expensive queries or analytics
7-Cache expensive calculations or db queries
8-Divide monolith to micro services so that you don’t have to deploy every line of code to every machine and you can scale one part of your application independent from others
9-Where necessary use a queue system to communicate between micro services
10-Start using non relational databases like Cassandra or elastic search depending on business.