The lifeblood of rapid growth companies are customers who are energized by the product

This is Product Market Fit:

"a defined ideal customer profile, energized to purchase, use, tell their colleagues"

2 Stages of Product Market Fit

Stage 1  Startup  $0 -- $2/3M
'Define First Success'

Startups need to find a Product Market Fit that is successfully sold, delivered
This is Geoff Moore's idea of 'crossing the chasm'

Stage 2  Scale up  $3 -- $12M+ 
'Duplicate Proven Success'

'Scale up' businesses have a Product Market Fit that works, here the challenge is to duplicate the success with new customers/employees
Geoff Moore's wrote about this in his second book, 'Inside the Tornado'

Both Stages of Product Market Fit requires:

Clearly defined customer profile with pressure to purchase
Easy workflow integration, immediate improvement
Marketing/sales success duplicated by new employees