Update README.md

Author: tdebatty

README.md

@@ -113,6 +113,10 @@ public class MyApp {
 ## Weighted Levenshtein
 An implementation of Levenshtein that allows to define different weights for different character substitutions.
 
+This algorithm is usually used for optical character recognition (OCR) applications. For OCR, the cost of substituting P and R is lower then the cost of substituting P and M for example because because from and OCR point of view P is similar to R.
+
+It can also be used for keyboard typing auto-correction. Here the cost of substituting E and R is lower for example because these are located next to each other on an AZERTY or QWERTY keyboard. Hence the probability that the user mistyped the characters is higher.
+
 ```java
 import info.debatty.java.stringsimilarity.*;