What are the key components of Kant's categorical imperative?

Kant's categorical imperative enables us to decide how we ought to act, regardless of the consequences. It, therefore, differs to a hypothetical imperative (if I want X, I ought to do Y) and is strictly deontological. Kant suggests that we ought to act in a certain manner in order to fulfill our duty. We are able to have knowledge of our duties because we are, according to Kant, rational beings. This allows us to have a priori knowledge of our duties (knowledge which is available to us without, or before, experience). We can formulate the categorical imperative in three ways. Firstly, through the universalizability test. This makes us assess whether we could will that our behaviour be universalized, so that everyone was to perform it. If we can will this to be the case, then our actions are morally permissible. Secondly, Kant's principle can be seen formalised through the ends-means distinction. According to Kant, we ought to treat people as ends, rather than means to our own ends. This enables us to reach the final formalisation of the principle - the kingdom of ends - which is an environment in which we respect the rationality that our fellow humans possess.