matplotlib has a very flexible function called pyplot.text(), that displays text:

import numpy as np
import matplotlib.pyplot as plt
X = np.linspace(-4, 4, 1024)
Y = .25 * (X + 4.) * (X + 1.) * (X - 2.)

plt.text(-0.5, -0.25, 'Brackmard minimum')

plt.plot(X, Y, c = 'k')
plt.show()

This script displays text next to a curve:

We use the pyplot.text() function that takes a position and the text to display. The position is given in the graphic coordinates, specifying the position of the left border and the vertical baseline of the text.

matplotlib's text rendering is very flexible. Let's explore the important options available.