Category is the old and best default taxonomy that allows you to keep your blog content classified. Category allows your visitors to easily browse articles they are looking for in your weblog. This tutorial explains you how you can add a category search filer because default WordPress search doesn’t provides you any such kind of filter. Using a category search you can make search very easy for your blog readers.
You can easily change the per page results in Google search according to your needs. Although the results Google offer per page by default is perfect but sometimes in special conditions you might like doing so may be if your internet connectivity is low at your place and clicking next page in search results is irritating you or if you spend more time in searching content on Internet and you want to see more results per page etc etc.