Bibliometrics is a set of mathematical and statistical methods used to analyze and measure the quantity and quality of books, articles, and other forms of publications. There are three types of bibliometric indicators: quantity indicators, which measure the productivity of a particular researcher; quality indicators, which measure the quality (or "performance") of a researcher's output; and structural indicators, which measure connections between publications, authors, and areas of research. Bibliometric indicators are especially important for researchers and organizations, as these measurements are often used in funding decisions, appointments, and promotions of researchers. As more and more scientific discoveries occur and published research results are read and then quoted by other researchers, bibliometric indicators are becoming increasingly important. This article provides an overview of the currently used bibliometric indicators and summarizes the critical elements and characteristics one should be aware of when evaluating the quantity and quality of scientific output.