The square root of 4 is 2. This is because 2 multiplied by itself (2 × 2) equals 4. In mathematical terms, the square root of a number \( x \) is a value \( y \) such that \( y^2 = x \). Therefore, the square root of 4 can be expressed as:
\[ \sqrt{4} = 2 \]
Additionally, it is important to note that the square root function typically gives the principal (non-negative) square root. Hence, while -2 is also a solution to the equation \( y^2 = 4 \), \( \sqrt{4} \) is defined as 2.