PROC SQL in SAS is a powerful tool for querying and manipulating data within the SAS environment. It allows you to perform complex data analysis and reporting tasks using standard SQL syntax, making it easier to work with large datasets and perform sophisticated operations. Unlike base SAS data steps, PROC SQL operates on data sets as a whole, rather than row by row. This can lead to significant performance improvements when dealing with large datasets. It's crucial for data cleaning, transformation, and reporting in SAS. PROC SQL is integrated with other SAS procedures, allowing you to combine data manipulation with other analytical techniques. For instance, you might use PROC SQL to select and filter data, then use PROC REPORT to generate reports or PROC MEANS to calculate summary statistics on the filtered data.