Sometimes we need to test things without documentation. It's not easy but Dennis Martinez has some great tips on how to do it right for APIs.
We all know that the roles of testers and developers differ. But there are some common points, too. Bob Salmon lists out the three main activities that both can learn from each other.
Maciej Mikołajek put together a nice, comprehensive overview of the software tester's roles, responsibilities and behaviours that contribute to the team's success.
Additionally, Senuri Samindi described the differences between QA vs. QE vs. SDET roles.