Let me know if this is a "discussion" question. I recently started a new job (software development) with a much richer business domain than my workplaces for the past few years. I'm wondering, what's the best way to figure out the domain? Write functional tests? Ask my co-workers? Participate in workshops?
EDIT: In an attempt to focus this question, I want to focus on business processes.
Some clarifying details: The company has several main software applications that it sells to clients, that are modified to suit clients needs (this is part of the business model), and I will be working with multiple clients. There is an intranet that isn't very easy to use, and seems specific to App Development, and a Yammer, that is more general to the parent company.