diff --git a/source/statistics/bayes_theorem.rst b/source/statistics/bayes_theorem.rst
index ea2ac41..c8522a1 100644
--- a/source/statistics/bayes_theorem.rst
+++ b/source/statistics/bayes_theorem.rst
@@ -1,15 +1,31 @@
 Bayes' Theorem
 ---------------
 
-This page is inpired from `MathIsFun <https://www.mathsisfun.com/data/bayes-theorem.html>`__.
+This page is inpired from:
+
+* `MathIsFun <https://www.mathsisfun.com/data/bayes-theorem.html>`__
+* `Wikipedia <https://en.wikipedia.org/wiki/Bayes%27_theorem>`__
 
 Theorem
 =========
 
+The Bayes's theorem describes the probability of an event, based on prior knowledge of conditions
+that might be related to the event.
+To compute :math:`P(A|B)`, in other words, the probability of the event :math:`A` to happen, knowing that :math:`B`
+already happen, the following drawing can be used:
+
 .. figure:: figures/bayes_theorem.svg
     :align: center
     :width: 400px
 
+    :math:`\,`
+
+The red area represents :math:`P(B)=a3+a4`. Thus, to compute :math:`P(A|B)` we do:
+
+.. math::
+   P(A|B)=\frac{a3}{a3+a4}=\frac{P(A)P(B|A)}{P(A)P(B|A)+P(\neg A)P(B|\neg A)}=\frac{P(A)P(B|A)}{P(B)}
+
+This final formula is the Baye's Theorem.
 See the `3Blue1Brown video <https://www.youtube.com/watch?v=HZGCoVF3YvM>`__ for a better understanding.
 
 Example