For new investors, the biggest challenge isn't just picking the right investments — it is figuring out how to build a portfolio that can grow over decades without requiring constant attention.

Exchange-traded funds (ETFs) can make that easy, offering instant diversification and exposure to some of the world's best stocks.

With that in mind, here are three ASX ETFs that beginners (and experts) could buy, hold, and largely forget about while letting compounding do its work.

Betashares Global Cybersecurity ETF (ASX: HACK)

As we have seen recently with Qantas Airways Ltd (ASX: QAN), the rise of cyber threats isn't slowing down. Businesses, governments, and even individuals are investing heavily to protect sensitive data, and the companies powering that security are thriving as a result.

The Betashares Global Cybersecurity ETF gives investors exposure to a portfolio of global leaders in cybersecurity. This means companies like Palo Alto Networks (NASDAQ: PANW), CrowdStrike (NASDAQ: CRWD), and Fortinet (NASDAQ: FTNT). These are businesses with strong demand tailwinds, recurring revenue models, and, importantly, global customer bases.

For beginners, this fund offers a way to tap into a megatrend without the stress of trying to pick a single winner. As long as the digital economy keeps growing — and cyber threats remain a risk — this ETF is positioned to benefit.

iShares S&P 500 ETF (ASX: IVV)

If you're looking for a simple way to invest in the world's largest, most influential companies, the iShares S&P 500 ETF is hard to beat. It tracks the S&P 500 index, which includes 500 of the biggest businesses in the United States.

This isn't just about the tech giants like Apple (NASDAQ: AAPL), Microsoft (NASDAQ: MSFT), and Nvidia (NASDAQ: NVDA). It also holds global leaders in industries like consumer staples, healthcare, and financials — think Coca-Cola (NYSE: KO), Johnson & Johnson (NYSE: JNJ), and Bank of America (NYSE: BAC).

For beginners, this ASX ETF is an easy way to diversify into the U.S. economy, which remains a powerhouse for innovation and long-term growth. Iti s also backed by a long track record: the S&P 500 index has delivered an average annual return of about 10% over multiple decades.

Vanguard Australian Shares Index ETF (ASX: VAS)

While global exposure is essential, it is also important to have a solid foundation in the local market. The Vanguard Australian Shares Index ETF is one of the simplest and most cost-effective ways to do that, giving investors broad exposure to the top 300 companies on the ASX.

This ASX ETF includes household names like BHP Group Ltd (ASX: BHP), Commonwealth Bank of Australia (ASX: CBA), and Woolworths Group (ASX: WOW), providing a mix of miners, banks, and consumer staples that have historically paid reliable dividends.

For new investors, this fund could be a great anchor for a portfolio, while complementing growth-heavy global options like the Betashares Global Cybersecurity ETF and the Vanguard Australian Shares Index ETF.