what views good for?

i'm only perplexing whole thought views used rdbmses. say, i know perspective one. i also know i've used past.

but i wish certain i have consummate bargain perspective useful perspective shouldn't useful for. some-more specifically:

1. what perspective useful for?
   
   
   
   
   • are there any situations delicious perspective shouldn't one?
   
   
   • why perspective lieu something table-valued duty clamp versa?
   
   
   • are there any resources perspective competence useful aren't apparent during initial glance?
   
   

(and record, questions intentionally naive. partly visualisation check.)