Update README.md

README.md

@@ -25,6 +25,9 @@ It achieves the following results on the evaluation set:
 
 Perplexity of 10.40
 
+Perplexity: Perplexity is a measure of how uncertain or surprised the model is about its predictions. 
+It's derived from the probabilities the model assigns to different words or tokens.
+
 Perplexity Article: https://www.jmlr.org/papers/volume3/bengio03a/bengio03a.pdf 
 https://medium.com/@AyushmanPranav/perplexity-calculation-in-nlp-0699fbda4594