I want to execute my web app as http://localhost.
http://localhost
1) Go to conf folder in tomcat installation directory
conf
e.g. C:\Tomcat 6.0\conf\
2) Edit following tag in server.xml file
server.xml
3) Change the port=8080 value to port=80
port=8080
port=80
4) Save file.
5) Stop your Tomcat and restart it.