What is default administrator password for Tomcat?

When you want to deploy your application to tomcat server , you may do it using admin UI but how can you access it? Do you know default admin password?
Actually tomcat does not provide any default password. You need to add users to $TomcatHome/conf/tomcat-users.xml and provide role as manager-gui(For tomcat 7 and 8) and manager (For tomcat 6).

Default tomcat-users.xml

As you can see, there are no users defined in above xml.You can simply add user as below:

tomcat-users.xml

You need to use role as manager-gui for tomcat 7, tomcat 8 and manager for tomcat 6