Who is considered a liberal?

I'd like to ask, what criteria are typically used to define someone as a liberal? Is it their political views, economic ideologies, or social stances? Do they tend to support progressive policies such as increased taxes on the wealthy, expanded social welfare programs, and stricter regulations on businesses? Or is it more nuanced than that, with individuals having different interpretations of what constitutes liberalism? Ultimately, how does society determine who falls under the umbrella of being a liberal?