From the originall rail tutorial: http://ruby.railstutorial.org/chapters/a-demo-app#sec-a_user_tour
URIs designed as followings
/microposts
/microposts/1
Now consider if you want to organize each micropost into exactly ONE categorie (name is unique), what URI you will perfer?
/categories
/categories/123
/categories/jewelries
/categories/123/jewelries
/categories/jewelries/123
or singular counterparts
/categories
/categories/123
/categories/jewelry
/categories/123/jewelry
/categories/jewelry/123
Naming ReST resources is mostly a matter of taste. Just keep them coherent. If you choose to name
/categoriesto serve a list of category, choose/jewelriesto serve a list of jewelry.I prefer using singular,
/categoryfor a list of category,/category/123for one category. You can use singular or plural as long as every resource follow the same rule.