[DISCUSS] What is CRO in SEo?

In Search Engine Optimization the Conversion Rate Optimization is the major one. It can be defined in three dimensions.
Designers – Uses this method to optimize a client’s website with a main goal to maximize conversions.
Business Owners – Consider this as part of an online marketing strategy.
Visitors – Causes visitors to buy a product or service and/or promote an internet page to others.
SEO and CRO have three things in common: visitors, traffic generation, and results.
Please help me out how does it really helpful in work in SEO technique?