An equation refers to an equation containing unknowns. It is an equation that represents the equal relationship between two mathematical expressions (such as two numbers, functions, quantities and operations), and the value of the unknown quantity that makes the equation hold is called "solution" or "root". The process of finding the solution of the equation is called "solving the equation".

In mathematics, an equation is a statement containing one or more variables. Solving an equation involves determining which variables have values that make the equation valid. Variables are also called unknowns, and the value of the unknowns satisfying the equation is called the solution of the equation.