How do you explain a scree plot?

A scree plot is a graphical tool used in principal component analysis (PCA) to display the eigenvalues associated with each principal component. It typically shows eigenvalues on the y-axis and the component number on the x-axis. The plot helps to identify the "elbow" point, where the addition of more components yields diminishing returns in explained variance, guiding the decision on how many components to retain for further analysis. In essence, it visually represents the relative importance of each component in capturing the data's variance.