Robo-advisors have become tremendously popular over the last decade, and rightly so. They automate the investing process for you, making it simple to invest in a diversified portfolio of assets, and they charge much less than a typical financial advisor. So it’s little wonder that many investors have turned to them, and robo-advisors now manage hundreds of billions of dollars.

Here’s what a robo-advisor does and who the major players are, including a few hiding inside some of the big financial institutions you already know.

What a robo-advisor does

A robo-advisor is really just a fancy term for a financial advisor that automates the process of investing and financial planning. A robo-advisor uses the planning tools that a human advisor would use and crafts a portfolio based on your risk tolerance and when you need the money.

But a robo-advisor also does things that would be tedious, expensive or impossible for a human advisor to do. For example, robos automate the process of tax-loss harvesting so that you’re maximizing any taxable losses, even on a daily basis. It can also rebalance portfolios so your asset allocation stays on track. Other robos may provide further services, such as advanced goal planning, including making your investments more conservative as you near your goal.

Like a good human advisor, a robo-advisor tailors your investments to your needs. If you have a long-term goal such as retirement, the robo-advisor will tend to pick aggressive investments such as stock funds, which have a track record of high returns. If you have a short-term goal, the robo would likely select more conservative investments, such as bond funds or even cash.

To invest your portfolio, a robo-advisor typically uses exchange-traded funds (ETFs) that have certain characteristics, such as what they’re invested in (stocks, bonds, cash or some mixture), or a certain level of volatility, including very little volatility at all.

ETFs charge an expense ratio, which is a fee paid to the fund management firm based on how much you have in the fund. A typical expense ratio might be 0.05 percent to 0.35 percent per year, or $5 to $35 for every $10,000 invested. You pay these fees no matter which robo-advisor you select, but some robos offer funds with lower fees, so check what they’re charging.

With a robo-advisor, clients simply deposit money into the account, and the robo-advisor invests it according to the investment plan that’s been laid out. The client can access the robo-advisor account at any point of the day to see the current market value of the account and how it’s invested.

Biggest advantages of a robo-advisor

A robo-advisor really shines in a few key areas, especially where its automation gives it a real edge over human advisors. Robo-advisors can be very good at tedious or formulaic tasks, such as designing a portfolio based on your goals. (Human advisors excel at the more sophisticated and less-routine tasks – here’s how to decide which is better for you.)

• Value-added features: As mentioned above, robo-advisors stand out in features that would simply be too tedious for a human to handle such as daily tax-loss harvesting. They also make rebalancing a portfolio easy, and they automate and simplify the process of investing a client’s money.

• Simplicity: Investing with a robo-advisor is tremendously easy, because clients can simply send in money, and the robo does the rest. Investors don’t need to do anything else, and they can always check on the account or even adjust it, if needed, when their financial situation changes, for example.

• Cost: Robo-advisors tend to be much cheaper than traditional financial advisors because everything is automated. Robos typically charge a percentage of the funds you have invested with them, and that fee is often around 0.25 percent per year, or about $25 per $10,000 you have invested. That’s a significant difference from the typical 1 percent charged by human advisors. Some robos charge more, but offer higher levels of service, such as access to a human advisor. Some even charge no fee at all.

Who should get a robo-advisor?

A robo-advisor can be a great choice for many different types of investors, but they can be especially helpful to new investors or those who don’t want to spend much time thinking about or managing their portfolios. With a robo-advisor, you’ll spend some time setting up your account and answering a few questions to determine your goals and risk profile, but once that’s done you can just check on your portfolio a few times a year. It won’t require the regular monitoring that’s necessary if you’re managing the funds yourself.

Robo-advisors can also be a good fit for people who want many of the same services offered by human financial advisors, but at a much lower cost. While you may not be able to consult with a financial expert at a robo-advisor, though some do offer that service, you’ll still get a customized portfolio based on your needs and will probably only spend half the cost or less of a typical financial advisor. If you’re new to investing or looking for a “set it and forget it” approach, robo-advisors could be a great option to consider.

How to open a robo-advisor account

It’s surprisingly easy to open an account with a robo-advisor, and since they’re all web-based, you can get going at any time of the day or night. You’ll need some basic personal and financial information such as your Social Security number and bank account details, but you can usually open the account in 15 minutes or less.

Plus, you often don’t even need money to get started with many robo-advisors, though some may require that you deposit a nominal $5 to get going. However, others may require $100 or even $500 or more to start, but if that’s a concern, you have options to avoid an upfront deposit.

Once you’ve opened the account, the robo-advisor will use a questionnaire to gauge your risk tolerance and time horizon (i.e. when you need the money.) From there it will design a portfolio using ETFs that meets your parameters. The robo-advisor may ask other questions about your financial goals to further tailor your portfolio to your specific needs and situation.

Popular robo-advisors

Robo-advisors have grown a lot in the last decade, and many of the independent players – those that offer only robo-advisors – are the best known. However, other well-known financial players may also offer a robo-advisor as part of their total offering, so don’t assume the independent players such as Betterment, Wealthfront and Ellevest are the only game in town.

Betterment

Betterment is one of the larger independent players, and it requires no account minimum for the entry-level Digital account, which charges a management fee of 0.25 percent. If you’re looking for more access to certified financial planners, you can step up to Betterment Premium for a 0.4 percent fee, but you’ll need to plunk down at least $100,000 in the account.

Wealthfront

Wealthfront requires a $500 account minimum and charges a 0.25 percent management fee. Wealthfront offers low expense ratios on its ETFs, no additional account fees and goal-based planning.

Ellevest

Ellevest is a newer player, and while it specifically markets itself to women (because traditional planning may not meet their needs), it’s suitable for anyone looking for client-first advice. It offers subscriptions at $12 per month providing an array of services, rather than a fee based on your assets under management. Company founder Sallie Krawcheck has been a force in the financial world trying to provide women services that meet their specific situation.

Schwab Intelligent Portfolios

You might hear “Charles Schwab” and think “discount broker,” but this financial powerhouse also runs the second-largest robo-advisor. While you’ll need more money than other robos to get started – a hefty $5,000 – you won’t pay any management fee. You can also upgrade to the Premium offering, which requires a $25,000 deposit, $300 start-up fee and $30 monthly fee. But you’ll also have unlimited one-on-one access to a certified financial planner.

Vanguard Digital Advisor

And the top robo-advisor by assets under management is Vanguard, which is best known for its lineup of low-cost funds. Vanguard Digital Advisor takes some coin to start investing – at least $3,000 – and you’ll pay an all-inclusive fee of 0.20 percent, instead of separate management and fund fees.

Other larger financial players such as Merrill and Citibank have entered the robo-advisor field as well.

Bottom line

While you might feel hesitant to trust your money to a computer app, robo-advisors are actually quite sophisticated. In fact, your traditional human advisor is likely using one anyway to create and manage your portfolio. Robo-advisors provide many attractive services for a reasonable cost, and their ease of use makes them particularly appealing to new investors looking to get started.