How to judge whether the photographic exposure is accurate according to the histogram display on the negative or digital camera?

The white part is all concentrated somewhere in the picture, which shows that the contrast of the image is low.

The white part is scattered, and the leftmost and rightmost parts are higher, indicating that the image contrast is large.

The white part is all to the left, and the column of the leftmost pixel is towering, which means that it is underexposed and the black field overflows.

The white part is all to the right, and the column of the rightmost pixel is towering, which means overexposure and white field overflow.