# What does Y-axis mean in a KDE plot?

Y-axis represents the PDE (probability density estimate) which is defined as probability per unit value of whatever variable is on X-axis. It’s values are used relatively to compare points on the graph. It is also termed as *probability differential* – probability of a point occurring between two values x1 and x2, represented by the area under the curve between those two points.

- PDEs can take values either <1 or >1.
- The area under the KDE plot is always 1.