Vertical search denotes search engines that specialise in the work of indexing and retrieving content within a certain niche or type. On the contrary, standard web search engines crawl and index the worldwide web; vertical search engines work toward a definite vertical such as images(represented by Google Images), videos(YouTube), news(Google News), or shopping(Google Shopping). Having these specialised focus areas allows Search Engines to give out more pertinent and targeted results to users looking under such specialised parameters. For example, a woman comparing prices on products may find it fit to go to some shopping search engine to make purchases, while anybody looking for an appropriate video could go to some video search engine, for example, YouTube. Just as the name indicates, vertical search engines have algorithms and indexing principles that are specifically attuned to the special kinds of content they index. They offer specialised features and filters concerning the vertical being addressed, for example, image size and colour filters that image search uses or price range filters that are applicable in shopping search. With the advent of vertical search, the need to optimise content by website owners for particular verticals is taking on increasing importance besides general web search.