diff --git a/scikit-learn/pca/README.md b/scikit-learn/pca/README.md
index b7a52ae..43f5369 100644
--- a/scikit-learn/pca/README.md
+++ b/scikit-learn/pca/README.md
@@ -8,6 +8,7 @@
 
 ## The goal
 
+PCA allows to extract an orthogonal basis system for a set of data. 
 
 Questions to [David Rotermund](mailto:davrot@uni-bremen.de)