Idea behind of placing on of this widget on your site is to bring more interaction with you user. A lot of times user lands on your website, tries to find something and leaves without any result. This widgets specifically designed for this purpose. They helping user to find something fater, navigate to some place better, suggest something based on what users tries to find.

Know your user. When somebody lands on your website you don't know anything about. For example pets user comes to pet website so we don't know if he pet owner or he is looking to get one. This small detail may tottaly change the game. Depending who are your user pet owner or something else you may show variable content to him.

Widgets are constantly learning user behavour and and may ask for feedback to find out if user are happy with service.