There are 3 types of parameters are possible

  1. Form parameters
  2. Servlet initialization parameters
  3. Context initialization parameters

These Parameters carry information into the the web application from outside world.

Within the servlet we can perform only read operation and we can’t perform any modification operation.Hence we can’t use parameters for information sharing with in the web application between the components.

For storing and sharing the information with in application attributes concept has introduced.

Based on our requirement a servlet can create a new attribute or can modify the value of existing attribute or can remove an attribute.

To store these attributes Servlet specification provides the following three scopes.