One can move through the framework using constraints, starting with clear, ending with chaos. Each imply a different way to act and approach the situation.
Clear systems have fixed constraints that can break catastrophically and can be repaired easily if you know what you are doing. Think of a water leak. If you know how to repair it, it is a simple matter to do so. If you don't, you fall off that cliff into Chaos quite quickly, and it takes a lot of time to get back to normal.
Complicated systems allow for a little more latitude in practice and so have governing constraints, such as laws and procedures. Break them at your peril, but also discuss them to make sure they govern activity in the system well. It's the domain of experts, for example doing taxes for a large organisation. It can be very complicated but there are clear right and wrong ways of doing it.
Complex systems are characterized by enabling constraints which give rise to all manner of creativity, emergence and self-organization, but which can also be immutable. Think of the laws of physics or principles of evolutionary biology that seem to generate a huge variety of systems and living beings. But we don't have a creature that can breathe by oxidizing neon, because neon doesn't oxidize. Constraints in complexity can be quite tight and still contribute to emergence and creative action.
Think of a flock of birds. Their is not a plan or director they follow in creating their beautiful patterns. Rather, simple rules like flying a set distance from your neighbour offer guidance. These simple constraints give rise to tremendous creativity and beauty within a distilled form.
In Chaos the absence of constraints means that nothing makes much sense, and all you can do is choose a place to act, sense what comes next, and act accordingly.
In chaotic situations one could also add constraints to regain control, this is what first responders do. They stabilize the situation and then figure out whether acting is responsible or whether the situation needs to be studied a bit more (so we know how a pandemic actually occurs and the different ways a new virus operates in the human body). However, this usually involves a tradeoff, for example in a pandemic applying a lock down allows regaining control at the expense of economic progress.
While you can find examples of all these domains around you, we are particularly interested in systems that behave in Complex ways (to be even more technical: Complex Adaptive Systems), for example Ecosystems.