Federal education legislation continues to emphasize the role of assessment in elementary and secondary schools. Perhaps most prominently, the Elementary and Secondary Education Act (ESEA), as amended by the Every Student Succeeds Act (ESSA; P.L. 114-95), requires the use of test-based educational accountability systems in states and specifies the requirements for the assessments that states must incorporate into state-designed educational accountability systems. These requirements are applicable to states that receive funding under Title I-A of the ESEA. As student assessments continue to be used for accountability purposes under the ESEA as well as in many other capacities related to federal programs (e.g., for identifying students eligible to receive extra services supported through federal programs), this report provides Congress with a general overview of assessments and related issues. It discusses different types of educational assessments and uses of assessment in support of the aims of federal policies. The report aims to explain basic concepts related to assessment in accessible language, and it identifies commonly discussed considerations related to the use of assessments. The report provides background information that can be helpful to readers as they consider the uses of educational assessment in conjunction with policies and programs. This report accompanies CRS Report R45049, "Educational Assessment and the Elementary and Secondary Education Act," by Rebecca R. Skinner (see ED597862), which provides a more detailed examination of the assessment requirements under the ESEA.