Most Efficient way to organize database with data for seperate organizations

Question

So this is more of a theoretical question. I am fairly new to databases, but here is my issue. I have a website which has users which will be divided up into different organizations. These organizations have nothing to do with each other, would I want to store them all in separate databases? different tables? or store them in the same databases and tables with columns to specify which organization they are a part of? Currently using SQLite but willing to move.