Conversion Rate Optimization (CRO) entails a methodical process aimed at amplifying the percentage of webpage visitors who carry out a desired action. This action can encompass a range, from form completion to becoming customers through purchases or subscribing to services.

Step-by-Step Breakdown of CRO:

1. Research and Analysis: The initial phase involves comprehending your audience and their behavior on your site. This necessitates studying website data, user behavior, and feedback. Tools like Google Analytics, heatmaps, and user surveys can yield valuable insights.

2. Identifying Key Performance Indicators (KPIs): KPIs quantify objectives reflecting business performance. In the context of CRO, KPIs could encompass conversion rates, bounce rates, average time on page, and more.

3. Setting Conversion Goals: A conversion goal denotes the specific action you wish site visitors to undertake. This might span making purchases, subscribing to newsletters, downloading content, or other actions valuable to your business.

4. Creating Hypotheses: Informed by insights from research, hypotheses are formulated for website/app changes that could elevate conversion rates. For instance, altering the color of a 'Buy Now' button might increase visibility and clicks.

5. A/B Testing: This phase entails testing hypotheses. A/B testing creates two webpage versions (Version A and Version B), with Version B integrating the hypothesized enhancement. Traffic is then divided between the versions, and their performance measured against KPIs.

6. Analyzing Results and Implementing Changes: Post A/B testing, results are assessed. If Version B performs notably better, implementing the changes permanently becomes a consideration.

7. Repeat: CRO is a continuous process. Even after initial improvements, testing and optimization persist.

Example Scenario:

Consider running an e-commerce store. You notice users add items to their cart but often fail to complete purchases. The hypothesis arises that the checkout process may be cumbersome, causing cart abandonment.

To validate this hypothesis, you simplify the checkout process, reducing steps and eliminating redundant fields. An A/B test follows: half experience the original process (Version A), and the other half the streamlined process (Version B).

After several weeks of testing, results are analyzed. The simplified checkout process prompts significantly more purchases than the original. Based on these findings, you opt to adopt the simplified process for all users.

This represents a fundamental CRO instance. In practice, CRO employs diverse strategies and techniques, often demanding ongoing testing and optimization to enhance conversion rates.