The Kannada script or the Kannada Lipi is basically derived from the ancient script of Brahmi.
There was an off-shoot from the original Brahmi script during the early 3rd century BC; this off-shoot gradually was developed as the script for Proto-Kannada. During the 4th century AD this script developed into the Kadamba script which again was derived as the Old Kannada script that existed till the 10th century AD. It is this Old Kannada script that is the mother of the modern day Kannada and Telugu scripts. So, it can be said that both Telugu and Kannada scripts have evolved from the same base of the ancient Brahmi script.
Kannada script is also used to write some of the other South Indian languages such as Kodava, Konkani and Tulu. Apart from the Devanagri script it is the script used to denote the second highest number of other languages. There is a historic evidence of Kannada being used in writing Badaga language of the Nilgiri region and also the Konkani in the Goa region where the script was named as Goykanadi. The present day Telugu script was derived from the Old Kannada script between the 11th and 14th century AD.