Final answer:
The FROM clause in SQL is used to specify the table or tables from which to retrieve data. If it is not used, the database engine will not know where to retrieve the data from and the query will result in an error.
Step-by-step explanation:
In the context of databases and SQL, the FROM clause is used to specify the table or tables from which to retrieve data. If you do not use the FROM clause, the database engine will not know where to retrieve the data from, and the query will result in an error.
For example, consider the following query:
SELECT name FROM students;
This query retrieves the column 'name' from the table 'students'. Without the FROM clause, the database engine does not know which table to retrieve the 'name' column from.