Building a custom search engine in your own expertise area may seem a trivial task. However, most of the data you need to create this special search engines is tacit knowledge . For example, one of the basics of building a custom search engine is assembling a list of websites in your chosen topic. However, assembling a unique list is critical when trying to follow copyright laws. You may recognized quality website when you re-stumble it,

Back in 2005, topical search was the driving force behind many startups. With qualities like relevancy and targeted audience , topical search engines quickly became the desired object of general search companies like Google or Microsoft. Today, nearly every big search engine incorporate some sort of vertical search in its own interface )e.g. search wikipedia or how stuff works on Google, and you'll get "vertical" search box on the first result(,