Final answer:
An alias is a temporary alternate name assigned to a table or column in a database query, used to simplify references within the query.
Step-by-step explanation:
A alias is an alternate name temporarily assigned to a table in SQL. When querying a database, it is common to use aliases to make column names more readable or to temporarily rename tables for the purpose of simplifying complex queries. For example, if you have a table named "Employees" but want to refer to it with a shorter name in your query, you might use an alias like this:
SELECT e.employee_id, e.name FROM Employees AS e;
In this query, e becomes the alias for the Employees table. Using aliases is especially useful in joins where you might have multiple tables and you need to distinguish between columns with the same name that exist in different tables.