Earning Passive Income
Passive income is a very important pillar in the FIRE movement. You can truly achieve financial independence only after you have set up a strong and stable stream of passive income. This should generate you the money required for your expenses and be in sync with inflation.

Earning Passive Income and Extra money
There are a number of passive income streams:

Rental income
Interest from loans or deposits
dividends and bonuses from stocks etc

Getting extra or additional income on the side
This is when along with your full time job you are earning extra money to reach your FIRE goal sooner. There are a number of ways one can earn cash on the side, I will be covering a lot of these such as

Freelancing
Taking courses or creating content
Selling creatives such as music, photography, graphics etc
Low investment businesses that require little effort etc