So, you know how we live in a country with rules and leaders who make those rules? Well, some people believe that those rules and leaders aren't right and that there should be a different way to run things. That's where Hizb ut-Tahrir comes in.
Hizb ut-Tahrir is a group of people that wants to create a different kind of government. They believe in something called the caliphate, which is a type of government based on Islam that they think would be better for everyone. They want to bring this government to all Muslim countries and make them all part of this big caliphate.
However, some people think that Hizb ut-Tahrir wants to achieve this goal through violent means, but the group says that they don't believe in violence and that they want to make change through peaceful ways.
So, basically, Hizb ut-Tahrir is a group of people who want to create a new type of government based on Islam and want it to replace the current governments in Muslim countries.