Research impact is the demonstrable contribution that research makes to academia and society. Currently, there are many ways to measure and no single standard. Furthermore, as new metrics are developed, existing metrics may become less relevant.
Why measure or track research impact?
This guide covers some of the more common measures of researcher, journal, and article impact - what they are, how to find them, and what you should know to use them appropriately.
What "impact" do metrics have on promotion and tenure?
Those are decisions made by each department or college on campus. The best thing to do is to consult with the department chair or colleagues to learn what is useful in your discipline. You'll need a selection of tools and the set will vary by discipline.