Final answer:
The 'WHERE' clause in T-SQL is used to filter records to include only those that meet specific conditions in a query's result set, vastly improving the precision and efficiency of data retrieval.
Step-by-step explanation:
The 'WHERE' clause in T-SQL is used to filter records and specify which data should be included in the result set of a query. It serves as a conditional statement that retrieves only those records that fulfill a specified criterion. When a SELECT statement is issued, the WHERE clause can be used to filter results according to the criteria outlined, effectively controlling the data that is returned from the database.
For example, if you have a database table called Customers and you only want to retrieve customers from a specific city, you could use the following T-SQL command:
SELECT * FROM Customers WHERE City = 'New York';
This command will return only the records from the Customers table where the city is 'New York'.