The COUNT function is a crucial aggregate function in SQL. It's used to determine the number of rows that satisfy a specific condition or the total number of rows in a table. This is essential for understanding the size of your data and for performing calculations like averages or percentages. For instance, you might want to know how many customers have placed orders in the last month or the total number of products in stock. The COUNT function allows you to answer these questions efficiently. It's a powerful tool for data summarization and reporting. Unlike other aggregate functions that ignore NULL values, COUNT(*) counts all rows, including those with NULL values in the specified column. COUNT(column) counts only non-NULL values in that column. This distinction is important when dealing with potentially missing data.