When should you wear a tie?

Traditional formal business attire meant a business suit teamed with a dress shirt and a tie, a la Cary Grant. Today, there's confusion as men ape the Hugh Grant look which is all about doing away with the 'ties' that bind. 

When should you wear a tie? Read @ http://m.economictimes.com/features/corporate-dossier/etiquette-of-ties-and-knots/articleshow/18611256.cms