Matplotlib line plots and bar charts can include error bars. Error bars are useful to problem solvers because error bars show the confidence or precision in a set of measurements or calculated values. Bar charts without error bars give the illusion that a measured or calculated value is known to high precision or high confidence.
A Basic errorbar can be created with a single Matplotlib function call:
import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(0, 10, 50)
dy = 0.8
y = np.sin(x) + dy * np.random.randn(50)
plt.errorbar(x, y, yerr=dy, fmt='.k');