The above response is not correct and I can say that 'hash tags' can do a lot increasing traffic to your website. I think Hash tags are first seen in Twitter and recently Facebook is allowing its users to add them in posts. This is how a hash tag appears #RK and I use it on Facebook.
What is the use of Hash Tags?
Let me explain it in a blogger's view. Let's assume that you are a blogger and your niche is about gadgets. Being a blogger you obviously post updates in FB page and twitter daily and those posts may include various categories. So, its is difficult for a visitor to read all posts about a specific gadget. So, in such case you can use a hash tag in your posts for example, '#iPhone 5S.' This helps your visitors identify the all the posts related to iPhone 5S when they click that tag. However, that hash tag might have already been used by many users since it's a keyword.
How to draw traffic using HashTags?
Using hash tags in your posts i.e. posts with hash tags receive more engagement of your visitors. When you use hash tags wherever necessary, at least 50 per cent of your page visitors on Facebook or twitter followers clicks it. There is a scope for staying long time on your page and if at least half of them visit the clickable links (to your blog) in your page, that worked. Also, excess use of hash tags doesn't look good and may work negative so, limit your posts to just 2 tags.
Hope this helped you.