Google-search – Why don’t I see the text from Google’s excerpt when I visit a site

You can simply add additional keywords to your search. Adding keywords will always reduce the amount of results you get since it uses an AND search by default.

To prove that you can do this even when OR is used, try typing the following into Google's advanced search:

• all these words: a b
• one or more of these words: c OR d

You will notice that it results in the following Google query: a b c OR d

Thus, you can conclude that the OR operator only works on single words. In other words, you can think of your query as a b (c OR d).

Furthermore, if you try to include multiple words in one of the OR text boxes (e.g. let's use d e instead of d), you will get the query: a b c OR "d e".

I'm not sure why it's not available always as Google described about a year ago in their blog that the feature will eventually be available to all over the world.

The new feature is rolling out today and tomorrow on google.com in English for people using Chrome 9+, IE8+ and Firefox 3.5+, and we’ll be expanding to new regions, languages and browsers soon.

So it's possible that it hasn't reached my location(which would be weird considering the number of users in India).

Anyway, although the appearance of the button is not assured, you can still block sites from showing up on your search results from your search settings > block unwanted results.