How can we skip JSF life cycle steps?

In two scenarios we can skip the JSF life cycle steps:
1.Use immediate=true:
If set in UIInput(s) only, the process validations phase will be taken place in apply request values phase instead. Use this to prioritize validation for the UIInput component(s) in question. When validation/conversion fails for any of them, the non-immediate components won't be validated/converted.
If set in UICommand only, the process validation, update model values & invoke application phases will be skipped for any of the UIInput component(s). Use this to skip the entire processing of the form. E.g. "Cancel" or "Back" button.
If set in both UIInput and UICommand components, the process validation, update model values & invoke application phases will be skipped for any of the UIInput component(s) which does not have this attribute set. Use this to skip the processing of the entire form expect for certain fields (with immediate). E.g. "Password forgotten" button in a login form with a required and immediate username field and a required but non-immediate password field.
2.Use FacesContext.responseComplete(): 
Sometimes, an application might need to redirect to a different web application resource, such as a web service, or generate a response that does not contain JavaServer Faces components. In these situations, the developer must skip the rendering phase (Render Response Phase) by calling FacesContext.responseComplete.