The `AS` keyword in SQL is a powerful tool for modifying the way data is presented in query results. It allows you to rename columns or tables to make your output more meaningful and easier to understand. This is particularly useful when dealing with multiple tables or when you need to tailor the output to specific reporting needs. For example, if you're joining two tables and one table has a column named 'CustomerID' and the other has a column named 'Client_ID', using `AS` lets you rename one of these columns to a more consistent name, like 'Customer ID'. This improves readability and avoids ambiguity. Renaming tables with `AS` is also helpful when you need to refer to a table by a different name within a complex query. This can be crucial for subqueries or when you need to join multiple tables with similar column names without conflicts. It's a simple yet essential technique for data manipulation and presentation.