As a person reads the Qur'an, there may be areas where a verse needs to be explained, put into historical context, or framed in reference to other verses on the same subject. Also, the Prophet Muhammad may have given more insight into certain verses in his oral traditions, his personal conversations with members of the community. Muslim scholars throughout history have gathered and written commentaries on the Qur'an, called tafsir (“explanation” or “interpretation” in Arabic).

Explanation and commentary is especially important with the Qur'an, as it was revealed in parts over a twenty-three-year span. Many passages were revealed in response to specific events or problems that were faced in the community. In order to fully understand what was meant by a certain verse, one must also be familiar with the circumstances surrounding its revelation. In some cases, a ruling or verse of guidance only applies to the specific situation it was addressing; in other cases a decree is more universal.

One must also consider verses of the Qur'an in context with other verses on the same topic. The structure of the Qur'an is such that discussion of a given topic may be dispersed throughout the text. Without reading the other verses, one would have an incomplete understanding. For example, the legal rulings about divorce are described in five different chapters. An exegesis of the Qur'an would refer the reader to each citation and clarify the topic based on the scriptural, historical, and social context.