Web3, also known as Web 3.0, is the next generation of the internet, which promises a cohesive, decentralized network powered by blockchain technology. It aims to create an online environment where users have full control over their data, thereby democratizing access and reducing reliance on centralized authorities.

On the other hand, DeFi is disrupting our traditional understanding of financial systems. Utilizing blockchain technology, primarily Ethereum, DeFi offers a range of decentralized financial services— from lending and borrowing to insurance and trading— all without requiring intermediaries like banks or institutions.

As a CFO, it's worth noting several implications:

1. Efficiency and Cost-Effectiveness: With smart contracts automating numerous processes in the financial workflow, operations could become faster and more cost-effective, leading to potential savings in infrastructure and personnel costs.

2. Transparency and Auditability: Every transaction recorded on a blockchain is transparent and immutable. This unique feature can potentially simplify auditing while maintaining high levels of accountability and reliability.

3. Risk Management: DeFi platforms operate round-the-clock, eliminating the risk associated with traditional banking hours. However, they also introduce novel types of risks, such as smart contract bugs, platform instability, and regulatory uncertainties.

4. Access to New Investment Opportunities: DeFi protocols offer innovative investment opportunities, such as yield farming, liquidity mining, and token staking, that CFOs might consider for diversifying the company's investment portfolio.

However, this new frontier is not without its challenges. Regulatory ambiguity, volatility, security issues, and scalability problems are hurdles yet to be fully addressed.

Regardless, I firmly believe it's crucial for CFOs to thoroughly understand Web3 and DeFi. We must remain agile, adaptable, and continuously learn to navigate this new landscape effectively.

Together, let's explore the exciting opportunities and complexities this new era of finance brings!