A more thorough explanation:

Definition: A literacy test is a test that measures a person's ability to read and write. In the past, some states required people to take a literacy test before they could register to vote. However, this practice was banned by Congress in 1975.

Example: In the past, some states used literacy tests to prevent African Americans from voting. These tests were often unfair and difficult, and many people were unable to pass them even if they were literate. For example, some tests required people to read and interpret complicated legal documents or to write an essay on a difficult topic.

Explanation: The example illustrates how literacy tests were used to discriminate against certain groups of people, particularly African Americans. The tests were often designed to be difficult and unfair, making it difficult for people to pass them even if they were literate. This practice was eventually recognized as a violation of civil rights and was banned by Congress.