Consider the complex number $z = 3 + 4i$. To find the modulus of $z$, we use the formula for the modulus of a complex number, which is given by:
$$|z| = ext{sqrt}(a^2 + b^2)$$
where $a$ is the real part and $b$ is the imaginary part of the complex number. For the given complex number, identify the values of $a$ and $b$ and compute the modulus.