Charles Schwab will begin offering commission-free online trading for U.S. stocks, exchange-traded funds and options on October 7, the company announced Tuesday. Previously, each trade cost investors $4.95.

Commission fees are charged by a brokerage when you buy or sell a stock, ETF or other type of investment product. Traditionally, they range in price, depending on the company, from anywhere to $1 to $50.

That started to change a few years ago. Robinhood, an investment app, has offered commission-free stock trades since 2013. More recently, Vanguard, J.P. Morgan, Interactive Brokers and other firms have also announced their own free trade options, as brokerages lower costs to remain competitive, and on Wednesday T.D. Ameritrade announced its U.S. brokerage firm will begin offering free trades for its online stocks, ETFs, and options starting October 3.

That's a win for investors, who are benefiting from lower costs overall. Fees, including trade commissions, can eat into your investment returns, even if they are as low as $5 or $10, making avoiding them whenever possible the smart move.

While fewer fees are always a good thing for your investment account, there are a few things to keep in mind if you are thinking about switching to a brokerage offering free or discounted trades.