MySQL is certainly more popular, but that doesn't necessarily mean it is a better database from a technical standpoint. MySQL is a fantastic piece of technology

MySQL is certainly more popular, but that doesn't necessarily mean it is a better database from a technical standpoint. MySQL is a fantastic piece of technology and it will likely serve most of your needs if you are building websites. If you have used it before and are familiar with it there may not be a great reason to change. You also have to consider that databases are "sticky" products. Once the choice is made it is unlikely to change for the lifetime of the project due to high switching costs so there is not really an incentive to go out of your way to learn about multiple databases. MySQL was basically the default database for developing web applications from 1998-2013. (It is the "M" in the LAMP stack) It gained this position by being free to use, reliable and stable. This began a virtuous cycle where more companies catered to MySQL users. Deploying, managing, and MySQL was easier since everyone catered to the audience which drove a virtuous cycle of more developers using MySQL. A lot PostgreSQL's popularity can be traced to Heroku where it was the default choice for a database. Heroku made it even easier for developers to deploy their applications to the internet. Instead of having some janky build process you would just type "git push heroku master" and you changes would be live in a matter of minutes. This ease of deployment drove the virtuous cycle for PostgreSQL. For the web it's unlikely that choosing either database would be a mistake. They both are great options. Going into the technical reasons why I believe PostgreSQL is a superior if you don't know what to choose would be a separate post in and of itself, but I've already gone on long enough.