A graphical display showing the distribution of data values in a sample by dividing the range of the data into non-overlapping intervals and counting the number of values which fall into each interval. These counts are called frequencies. Bars are plotted with height proportional to the frequencies.
A point that is the left endpoint of one class interval, and the right endpoint of another class interval.
In plotting a histogram, one starts by dividing the range of all values into non-overlapping intervals, called class intervals, in such a way that every piece of data is contained in some class interval.
End Point Convention
In histograms, you need to decide where to count values that are on the exact boundary between two intervals: either in the left or in the right interval. You should always let readers of the histogram know which side is chosen.