"Growth hacking" is a business and marketing concept that has been building momentum, particularly among tech start-ups. Essentially, growth hacking is the concept of scaling a company or product quickly by making data-driven decisions. It also dictates how the product or company is marketed to potential customers. Growth hacking eschews traditional marketing channels for low cost "guerilla" tactics that promote rapid growth. A key tenet of growth hacking is that it encourages businesses to take an outside-the-box approach to marketing, taking all aspects of operations into consideration when identifying growth opportunities.
This process starts with incorporating growth into the product itself. When developing a product, it is critical to make sure there is "Product Market Fit". Essentially, this means that there is a market, or a need, for your product. If you are developing another "me-too" product or a product that doesn't address any existing issue or void in the market, then you will never succeed with a growth hacking approach. The key to growth hacking is that you are offering something new and noteworthy. Even after you have developed a product or service with Product Market Fit, this process requires you to constantly iterate. Growth hacking relies heavily on usage analytics to continuously improve your product.
Once you have Product Market Fit and have implemented a process of constant improvement, you must determine the best way to hack your growth. Again, you should identify tactics that are outside of typical marketing channels. A good example of growth hacking is the way that Gmail grew during its beta stage. Each Gmail user received a finite number of invitations to the service that they could share with friends. Not only did this strategy encourage users to proactively tell their friends about Gmail, but it added a level of exclusivity to the service, making it even more attractive to potential users. Another excellent example of a company effectively implementing a growth hacking strategy is Dropbox. Each user receives a modest 2GB of cloud storage when they sign up for a free account, but they receive an additional 500 MB of space for every person they refer to the service. Just like Gmail, this encourages users to share the service with their friends, and in this case, provides a tangible incentive for doing so. A more subtle growth hacking example is the default "Sent from my iPhone" email signature. This broadcasts to every one of your email recipients that you are staying productive on-the-go by using an iPhone. Most successful growth hacking tactics are essentially word-of-mouth or buzz marketing strategies, but implemented in an innovative or unique manner.
Identifying these opportunities should be the job of everyone in the company, not just the marketing department. In fact, many companies utilizing growth hacking don't even maintain a formal marketing department. Instead, marketing has become the job of every employee.