Different Types of Work
as referenced in The Phoenix Project,
there are multiple different kinds of work that a team does. I'm omitting a category (changes) for now, as it's effectively encompassed within the other categories.
The three are categorized as:
work that directly benefits the business
work that indirectly benefits the business (e.g. improving the existing process, to enable more feature work)
Incidents and outages that are not planned.