**Growth hacking definition:** Using math to make product and marketing decisions in tandem. The metric of success is profitable user acquisition.

If you are a professional, these are some alternative terms to use instead of Growth Hacking: User Acq, Growth Optimization, or just Growth.

The hacker term is a buzzword that can be safely ignored. It comes from the belief that people who are good at user acq somehow know a trick. They don’t. They just use data instead of gut feel to make decisions. They also work on marketing and product optimization at the same time instead of viewing those as separate disciplines.

“ Half of my advertising works, I just don’t know which half”

This quote pardons marketers for spending lots of money on things that can’t be measured. Growth Optimization is the opposite of this quote.

The growth approach is to only spend on channels where a profitable cost per acquisition can be calculated.

This is the equation:

Cost per click / Conversion rate = Cost Per Acquisition < Lifetime value.

When a growth optimizer is thinking about marketing, everything they do is in pursuit of balancing this equation.

The popularity of the growth hacker term comes from the belief that not only do they know how to acquire users, they know how to do it for free.

This This means that they have built a product in such a way that it achieves a viral coefficient.

This is the equation:

Invites sent per user * Conversion rate into a new user = Viral Coefficient.

When thinking about product decisions, a growth optimizer is primarily concerned with ways to increase the two variables in this equation.

#### Wrapping it up

A growth optimizer uses data to fill in the two equations listed above. They make product and marketing changes at the same time to optimize the variables in the two equations. Take a look at an example from the first equation.

$1 Cost per Click / 1% conversion rate = $100 Cost Per Acquisition < $50 Lifetime value

This equation doesn’t balance. We are spending $100 and the user is only making us $50. A growth optimizer would look at ways to change the two variables, cost per click and conversion rate. He could lower the cost per click in Adwords while increasing the conversion rate with product optimization. Either one is a lever in reducing the cost per acquisition.

.70 cost per click / 1.5% conversion rate = $46 Cost Per Acquisition < $50 Lifetime value.

That’s pretty much it. This may seem obvious in retrospect, but it’s a complete 180 from how most startups operate.