Servlet technology was introduced to overcome the limitations of CGI technology. These drawbacks are:
Servlet technology is better than the CGI in performance with the respect of the timing process. It is possible because Servlet uses the multithreading technology. By this, a new thread has been created at every request which is faster than the loading generating fresh request Object for every request with CGI
Servlet technology is better than CGI in memory utilization.
It is efficient to use Servlets as the web application that develops on it can work on a standard web container, for example, JBoss, Tomcat, Glassfish servers.
It can also run on several operating systems like Linux, Windows, Solaris, Mac, Unix etc.
The very important point of choosing Servlet is that the users don't have to worry about the security, memory leaks, garbage collection etc. container maintain servlet
Servlets is easy to use as there is nothing to learn except business logic
Servlets are manageable and the knowledge trajectory is little.