Growth hacking is a marketing technique developed by technology startups which uses creativity, analytical thinking, and social metrics to sell products and gain exposure. It can be seen as part of the online marketing ecosystem, as in many cases growth hackers are simply good at using techniques such as search engine optimization, website analytics, content marketing and A/B testing which are already mainstream. Growth hackers focus on low-cost and innovative alternatives to traditional marketing, e.g. utilizing social media and viral marketing instead of buying advertising through more traditional media such as radio, newspaper, and television. Growth hacking is particularly important for startups, as it allows for a "lean" launch that focuses on "growth first, budgets second." Facebook, Twitter, LinkedIn, AirBnB and Dropbox are all companies that use growth hacking techniques.
Sean Ellis coined the term "growth hacker" in 2010. In the blog post, he defined a growth hacker as "a person whose true north is growth. Everything they do is scrutinized by its potential impact on scalable growth." Andrew Chen introduced the term to a wider audience in a blog post titled, "Growth Hacker is the new VP Marketing" in which he defined the term and used the booking agency AirBnB's integration of Craigslist as an example. He wrote that growth hackers "are a hybrid of marketer and coder, one who looks at the traditional question of 'How do I get customers for my product?' and answers with A/B tests, landing pages, viral factor, email deliverability, and Open Graph." In 2012, Aaron Ginn defined a growth hacker on TechCrunch as a "mindset of data, creativity, and curiosity."
The most popular deck ever created on growth hacking is "Growth Hacking or: Lean Marketing for Startups" by Mattan Griffel. In it, Griffel defines growth hacking as "a set of tactics and best practices for dealing with the problems of user growth." 
Also in 2013 a resource known as Growth Hacker TV interviews top growth hackers at companies involved with the early movements such as Dropbox, LinkedIn, Expedia, Twitter, and Facebook.
In late 2013, growth hacking also found its way into the Asian entrepreneurship scene. The leading resource for growth hacking in the region is Growth Hacking Asia, which was launched with the goal to increase the success rate of Asian start-ups.
Fast Company defined the problem facing most startups as 1) they don't have the money and 2) they don't have a traditional marketing background. To combat this lack of money and experience, growth hackers approach marketing with a focus on innovation, scalability, and user connectivity. Growth hacking does not, however, separate product design and product effectiveness from marketing. Growth hackers build the product's potential growth, including user acquisition, on-boarding, monetization, retention, and virality, into the product itself. Fast Company used Twitter "Suggested Users List" as example: "This was Twitter's real secret: It built marketing into the product rather than building infrastructure to do a lot of marketing."
The heart of growth hacking is the relentless focus on growth as the only metric that truly matters. Mark Zuckerberg, best known of the 5 co-founders of Facebook, is said to have had this mindset while growing Facebook. While the exact methods vary from company to company and from one industry to the next, the common denominator is always growth. Companies that have successfully "growth hacked" usually have a viral loop naturally built in to their onboarding process. New customers typically hear about the product or service through their network and by using the product or service, share it with their connections in turn. This loop of awareness, use, and sharing can result in exponential growth for the company.
Besides Twitter, Facebook, Dropbox, Pinterest, YouTube, Groupon, Udemy, and Instagram are all companies that used and still use growth hacking techniques to build brands and improve profits.
An early example of "growth hacking" was Hotmail's inclusion of "PS I Love You" with a link for others to get the free online mail service. Another example was the offer of more storage by Dropbox to users who referred their friends.
- Holiday, Ryan (December 17, 2012). "Everything is Marketing: How Growth Hackers Redefine the Game". Fast Company.
- Ginn, Aaron (September 2, 2012). "Defining a Growth Hacker: Three Common Characteristics". TechCrunch.
- Biyani, Gagan (May 5, 2013). "Explained: The actual difference between growth hacking and marketing". The Next Web.
- Hockenson, Lauren (May 18, 2013). "Growth Hacker: A Buzzword Surrounded by Buzzwords". Mashable.
- Ginn, Aaron (September 7, 2012). "Defining a Growth Hacker: 5 Ways Growth Hackers Changed Marketing". TechCrunch.
- Emerson, Rip (January 13, 2013). "Chamath Palihapitiya On Growth Hacking And How To Create A Sustainable User Acquisition Engine". TechCrunch.
- Ellis, Sean (June 26, 2010). "Find a Growth Hacker for Your Startup". Startup-Marketing.com.
- Holiday, Ryan (July 8, 2013). "The Secret That Defines Marketing Now". Fast Company.
- Chen, Andrew. "Growth Hacker is the new VP Marketing". AndrewChen.co.
- Ginn, Aaron (n/a). "What is a growth hacker?". Aginnt.com. Check date values in:
- Ellis, Sean (March 31, 2014). "This is the most popular deck ever created on "growth hacking"". Twitter.
- Griffel, Mattan (August 22, 2012). "Growth Hacking or: Lean Marketing for Startups". Slideshare.
- Griggs, William (May 10, 2013). "6 important lessons from this year’s Growth Hacker Conference". Venture Beat.
- Ginn, Aaron (October 21, 2012). "Defining a Growth Hacker: Building Growth Into Your Team". TechCrunch.
- Ginn, Aaron (October 28, 2012). "Build it and they won’t come: How and why growth hacking came to be". The Next Web.
- Holiday, Ryan (June 11, 2013). "Here’s Some Marketing Advice: Your Product Is Terrible". Medium.com.
- Ginn, Aaron (October 20, 2012). "Defining A Growth Hacker: Growth Is Not A Marketing Strategy". TechCrunch.
- Jarvis, Chase (February 22, 2013). "From Obscurity to Internet Sensation — How Creatives Can Win the PR Game with Ryan Holiday". ChaseJarvis.com.
- Ellis, Sean. "Sean Ellis On Growth". medium.com. Medium. Retrieved 16 August 2014.
- Kagan, Noah. "How My Blog Homepage Redesign Increased Email Signups By 300%". blog.hubspot.com. Hubspot. Retrieved 16 August 2014.
- Chen, Andrew. "What's Your Viral Loop? Understanding The Engine Of Adoption". andrewchen.co. Retrieved 16 August 2014.
- Ellis, Sean (June 24, 2014). Startup Growth Engines: Case Studies of How Today's Most Successful Startups Unlock Extraordinary Growth. Sean Ellis and Morgan Brown. Retrieved 16 August 2014.
- Ginn, Aaron (December 8, 2012). "Defining A Growth Hacker: Debunking The 6 Most Common Myths About Growth Hacking". TechCrunch.
- Johns, Andy (May 11, 2012). "Facebook Growth and Traction: What are some decisions taken by the "Growth team" at Facebook that helped Facebook reach 500 million users?". Quora.
- Johns, Andy (April 30, 2012). "What is Facebook's User Growth team responsible for and what have they launched?". Quora.
- Holiday, Ryan. "Don Draper Is Dead: Why Growth Hack Marketing Is Advertising’s Last Hope". BetaBeat.
- Adams, Scott (July 10, 2014). "joke of the day".