The book presents several main ideas:

1. Red Oceans vs Blue Oceans: The authors contrast two types of marketplaces: Red Oceans and Blue Oceans. Red Oceans represent all the industries in existence today, where companies try to outperform their rivals to grab a greater share of the existing market. In such a market, boundaries are defined and accepted, and the competitive rules are known. However, these markets are often crowded and competition is intense, likened to a bloody "red" ocean.

On the other hand, Blue Oceans denote all the industries not in existence today, the unknown market space. This is the space of business growth and opportunity. In Blue Oceans, competition is irrelevant because the rules of the game are waiting to be set. It's about creating and capturing new demand, not fighting over existing customers.

2. Value Innovation: Value Innovation is the simultaneous pursuit of differentiation and low cost, creating a leap in value for both buyers and the company. The idea is not to compete within the confines of the existing industry or try to steal customers from rivals but to create new demand and make the competition irrelevant.

3. Four Actions Framework: The book suggests a framework for creating Blue Oceans by asking four key questions to challenge an industry's strategic logic and business model:
   1. What factors that the industry takes for granted should be eliminated?
   2. Which factors should be reduced below the industry's standard?
   3. Which factors should be raised well above the industry's standard?
   4. What factors should be created that the industry has never offered?

4. Strategy Canvas: The Strategy Canvas is a central diagnostic tool and an action framework. It graphs a company’s performance across its industry’s factors of competition to understand where the competition is investing, what customers receive from those investments, and where there are opportunities to break away from the competition by offering new, compelling values.

5. Six Paths Framework: The book also offers a Six Paths Framework to find Blue Oceans. These paths challenge six basic assumptions that underpin many industry structures.

6. Overcoming Key Organizational Hurdles: The authors discuss the common hurdles to implementing blue ocean strategy, such as cognitive, resource, motivational, and political hurdles. They offer methods to overcome these barriers.

7. Building Execution into Strategy: Kim and Mauborgne propose that strategy should be built around robust execution principles. They suggest three key principles: Fair process, trust and commitment, and risk taking.

Key lessons from the book include:

1. Companies should focus on making competition irrelevant by creating a leap in value for both the company and its customers.
2. Innovation can often come from looking outside your own industry. The key to making a Blue Ocean Strategy work is to focus on value innovation.
3. When it comes to winning market share, the key isn't to beat the competition but to make the competition irrelevant.
4. Organizational hurdles to change and innovation can be overcome through careful and consistent management.
5. Execution should be a central part of the strategy. The company's leaders must be committed to 'blue ocean leadership' – where they focus on acts and activities, and encourage employees to problem-solve and innovate.

The overall idea is that success comes not from battling competitors, but from creating 'blue oceans' - untapped new market spaces ripe for growth. The authors argue that lasting success comes from creating 'blue oceans': untapped new market areas ripe for growth. They provide a systematic approach to making the competition irrelevant and outline principles and tools any company can use to create and capture their own blue oceans.