Google has released a blog post today outlining the new updates coming to Google Now on Tap very soon. Google knows that oftentimes Google Now on Tap won't be able to make sense of a long email or a screen with a lot of text and images. Now on Tap users will be able manually set where they would like to target Google's search to take place. An example would be if someone were to summon Google Now on Tap while reading a long article where they only wanted to search for the definition of a single word. This should let users have a better experience in the case that a large amount...
Source: http://www.gsmarena.com/google_now_on_tap_to_receive_new_features-news-18567.php