Application is a group of modules which provides its related information.For example change application provides the information related to change process. It consist of modules like create change ticket,view change tickets etc.
View defines the arrangement of fields on a form or a list. For one single form we can define multiple views according to the user preferences or requirement.
Q. What is ACL?
An ACL is access control list that defines what data a user can access and how they can access it in service now.
Impersonating a user means that you can log in to the system as that user and can have feel how the service-now UI is set for that user.This is very useful while testing.For example if you are required to test that a user can access change form or not.You can impersonate that user and can test instead of logging out from your session and logging again with that user credentials.
Dictionary Overrides provides the capability to override several properties of a field in extended table.For example change table is extended from task table.There is a field named status in task table and set as read-only.When we use this field in change form it will show be a read only.We can set this to non-read only by using the dictionary override.Similarly there are other properties that can be set for the fields in extended table.
UI policies are alternative to client scripts.It can be used to set a field as mandatory, readonly and visible on a form. You can also use UI policy for dynamically changing a field on a form.
Data policy checks the mandatory and read-only of a field whenever a record is inserted or updated through a web-service or import set.For example: If a mandatory field in the incoming record (from import set or web-service) is empty then the data policy will not allow to insert that record into the table.
UI policy acts when a record is inserted or updated through a servicenow UI i.e servicenow forms while data policy acts whenever a record is inserted or updated into database through any means.
Client script sits on the client side(the browser) and run there only.types of client script are OnLoad() OnSubmit() OnChange() OncellEdit)(