What is the integral of x?

The given integral is an indefinite integral of $x$. We can write $x$ as $x^1$.

The power rule for integration states that $\int x^n\,dx = \frac{x^{n+1}}{n+1} + C$, where $n \neq -1$.
For $\int x^1\,dx$, we have $n=1$.

The final answer is $\frac{x^2}{2} + C$.