Why are some maven projects in IntelliJ grayed out?

Why are some maven projects in IntelliJ greyed out?

Answer

Seems images are better way to answer this question.

1. Projects are greyed out when you ignore them in your IntelliJ workspace.

2. To add those projects or modules back in your workspace, right click on them and click on unignore projects as shown in below screenshot.

3. Alternatively, you can also go to File – Settings -> Build, execution and deployment -> Build Tools -> Maven -> Ignored Files, now select whichever projects/modules you may wish to retain in your IntelliJ workspace.

Feel free to ping in comments if more clarification required. Happy coding.