With so many being shared everyday, can a #hashtag change anything? Well yes it can. And let me tell you how. 

This little # has done some great things. In fact #hashtags have been a force for good since we started using them back in 2009. They have brought communities together during times of tears, tragedy and tribulation. They have helped us laugh, cry, shout and moan, amplifying our feelings and emotions on all sorts of issues. 

And there is no better example of how the #hashtag collectively described our feelings following the terror attacks in Paris and Sydney. #JeSuisParis (and #PrayforParis) was the most popular #hashtag of 2015 and demonstrated how connected we are in a geographically and culturally separated world. This worldwide outpouring of support, demonstrated perfectly why “glocalise” is now a word.

Another big #hashtag of 2015 was #BlackLivesMatter - used more than nine million times in 2015 by people who wanted to express their anger over a string of shootings involving the police and black citizens in Ferguson, Charleston and Balitmore in the US. It has become one of the biggest social movements in US history. 

Another big social issue - the legalisation of same sex marriages in Ireland and the US - led to the formation of #MarriageEquality - the third most used #hashtag on Twitter last year. And I cannot fail to mention my favourite of 2015: #refugeeswelcome which restored some faith in humanity but also highlighted the strength of feeling on an emotive and misunderstood issue. 

#Hashtags are everywhere. Pushed by Twitter in the early days, it is now used to title programmes, define issues and name products. It is a powerful tool in online communication and engagement and this little symbol helps to optimize content and conversations. A #hashtag instantly links a social media post to a group of others also talking about the same thing, creating a community of voices to discuss trending topics from comical to the most serious. 

The #BringBackOurGirls campaign has shown that social media is more than just pictures of selfies. When 200 Nigerian girls were kidnapped by Islamic militants in 2014 the issue became significant and one of international importance. But not at the start. Just a handful of people took to social media to express their horror at what had happened. It was not until a speech by the Vice President of the World Bank for Africa that the issue was brought to the attention of the world. In that speech he urged the Nigerian Government to "bring back our girls" which was quickly turned into a #hashtag and tweeted over one million times. 

The power of the # is of course best used in real time - something businesses and organisations don't often do. There is no point commenting on the X Factor final on Twitter three days after the winner is announced and adding the #xfactorfinal hashtag. Most people have commented and moved onto the next trending topic. It is the equivalent of turning up to a party 12 hours after it ended and trying to get partygoers off the sofa and out of their beds to start dancing again. Pointless. Or if I had a #hashtag for it - #gameover. 

However, in some cases, when an issue is so important, it can keep the conversation going for some time - great for social change makers who often struggle to keep their issues in hearts and minds. #refugeeswelcome is still being used. As is #BlackLivesMatter. The last tweet I saw using this hashtag was 24 minutes ago. It is the social issues that appear to have 'hashtag sustainability' and the list of most used #hashtags for 2014 and 2015 prove that. 

But the #hashtag doesn't come without problems. It is almost inevitable that with widespread social change comes an ugly, sometimes violent and bigoted pushback from those who do not like change. And this is something we have to become hard to as social marketeers and change agents. 

I have talked for some time about the power of social media for change. The #hashtag is just one tactic and of course all on its own it won't lead to social reform. Only real governmental pressure and action will lead to real and lasting change - but social media is helping Governments, businesses and organisations to listen - and act. Especially when enough people speak. 

Social media is the most shareable, durable and global collection of voices the world has ever seen, one which is increasingly difficult to ignore. Not all campaigns and #hashtags will go viral. Some may even take a while to get off the ground. There must be thousands of charities, brands and lobbyists launching new #hashtags every day and most of them don’t get further than a few people. 

But that doesn't mean you should ignore the #hashtag. Try to lead with your own #hashtag or consider jumping on the back of an established #hashtag. At the end of the day it is better to be in the conversation than out on the fringes -  or worse still, not in the conversation at all.

My guide to creating a 'powerful' #hashtag

Here are my top five rules for creating a good #hashtag. 

1. Be emotive. Pick a hashtag that describes an emotion or call to action. For example: #notinmyname, #lovenotwar #bringbackbaywatch #saveblackpooltower But make sure that it is easy to remember and crystal clear. 

2. Pick one. What #hashtag best describes your issue, brand, or cause? Don't clutter your campaign with several. If you can't sum up in a short #hashtag what you are trying to achieve you need to go back to the drawing board. 

3. Stick with your #hashtag for a while and have a plan on how you are going to build on it. Not all will go viral and some take time to catch on, so don't get frustrated if millions are not using it straight away. 

4. Add the #hashtag to your communications. Even though hashtags were born online, they can generate a buzz offline too. Placing a #hashtag in a public place can drive #hashtag use online. For example, adding the #hashtag to a bus stop poster might drive people to their social media to join the conversation. 

5. Get real. Use your #hashtag in real time and link it to what is topical and live. #BlackLivesMatter is used more at times when equality, crime and gun laws is on the news agenda. 

If you would like to talk to us about your campaign and how to create powerful #hashtags and social media campaigns please get in touch. We also run a course called social media for change for public and third sector organisations and businesses who want to 'do good'.