The y-intercept of the equation $y = -3x + 4$ is $4$.

In the equation $y = -3x + 4$, the y-intercept is defined as the point where the line intersects the y-axis. This intersection occurs when the value of $x$ is $0$. To determine the y-intercept, we substitute $x = 0$ into the equation. This yields:

Thus, the y-intercept is $4$.

The y-intercept is a significant characteristic of a linear equation expressed in the form $y = mx + c$, where $m$ represents the slope (or gradient) and $c$ denotes the y-intercept. In this particular case, the slope is $-3$ and the y-intercept is $4$. This indicates that the line crosses the y-axis at the point $(0, 4)$.

Understanding the y-intercept is crucial for graphing the line and analyzing its behavior. For example, knowing the y-intercept allows you to quickly plot the starting point of the line on a graph, facilitating a more accurate representation of the entire line.