Article/book impact: The value of particular works, such as journal articles, conference proceedings, and books, can be measured by the number times they are cited by other works and alternative metrics such as tweets, blog posts, likes, bookmarks, etc.
Journal impact: The importance of particular academic journals can be measured by the number of times their articles are cited and where they are cited.
Researcher impact: The success of particular researchers can be measured by the number of works they publish and the number of times their works are cited.
Institutional impact: The prestige of a department or area of research within an institution can be measured by the collective impact of its individual researchers compared to those at other institutions.
Impact factors remain an important means of measuring research influence and dissemination, but they have recently have become controversial in their role in tenure decisions, e.g. DORA (Declaration of Research Assessment, sponsored by the Association of Cell Biology), which makes "recommendations for improving the way in which the quality of research output is evaluated" with less emphasis (or even no reliance upon) on journal metrics. The Declaration has had its critics as well--see Kent Anderson's post at the Scholarly Kitchen.