In the world of Social Media, hashtags are everywhere! Once you hashtag a word on Twitter, Instagram, Google + and even Faceboo everyone can see it, all account users. The word goes directly into the hashtag world and this allows users who aren't following you to see it, and to see the message and/or content you post related to this word.
However, don't give in to temptation in creating a hashtag in every single word you use: Use them wisely, by subject, relevance and importance. The recommended ratio is 1-3 hashtag words per tweet/publication, or else you might be just missing the point and creating clutter in your social media profiles.