Ask HN: What are your favorite JetBrains IDEs “lifehacks”?

I use IDEs from JetBrains (such as IntelliJ, or PyCharm) as my daily development tools, and even after 2 years of using it, I still occasionally find some "hidden" feature, or shortcut, that simplifies my life a little bit, such as custom tab-completing templates, or class diagram generator and so on...

So, what are your favorite lifehacks on JetBrains platform, that are not universally known?