Secondary sources are documents or recordings that analyze, interpret, or summarize information from primary sources. They provide context and commentary on original materials, such as historical documents, interviews, or artifacts. Examples of secondary sources include books, articles, and documentaries that discuss events or topics based on firsthand accounts. These sources are valuable for research because they help to understand the significance of primary data. By synthesizing various perspectives, secondary sources can offer a broader view of a subject, making them essential for academic work, such as essays or research papers, where understanding the context is crucial.