股票佣金是指投资者在进行股票交易时需要支付给券商的费用。这包括买卖股票、基金、权证等证券产品的手续费。佣金的多少取决于投资者选择的券商和交易方式，一般来说，佣金费率在0.02%到0.3%之间，具体金额则根据交易金额而定。

股票佣金的存在是因为券商为投资者提供了交易服务，包括交易通道、交易软件、行情资讯等方面的支持。券商需要收取一定的费用来覆盖成本和盈利。同时，佣金也是投资者对券商服务质量和服务水平的一种评价标准。

对于投资者来说，了解股票佣金的构成和计算方式非常重要。投资者应该根据自己的交易频率和交易金额来选择适合自己的券商和佣金费率。此外，投资者还应注意佣金的收取方式和时间，以及是否可以调整佣金费率。

在选择券商时，投资者应考虑券商的信誉度、服务质量、交易软件性能、佣金费率等因素，并进行充分的调查和比较。通过选择正规、可靠的券商，投资者可以更好地保障自己的交易安全和合法权益。

英文段落：

What is Stock Commission?

Stock commission refers to the fee that investors need to pay to the brokerage firm when conducting stock trading. This includes the commission for buying and selling stocks, funds, warrants, and other securities. The amount of commission depends on the brokerage firm and trading method chosen by the investor, generally ranging from 0.02% to 0.3% of the trading amount, which is determined by the specific amount of the transaction.

The existence of stock commission is because brokerage firms provide trading services to investors, including trading channels, trading software, market information, and other supports. Brokerage firms need to charge certain fees to cover costs and profits. At the same time, commission is also an evaluation standard for investors to evaluate the service quality and level of brokerage firms.

For investors, it is very important to understand the composition and calculation method of stock commission. Investors should choose brokerage firms and commission rates that suit their own trading frequency and trading amount. In addition, investors should also pay attention to the charging method and time of commission, as well as whether the commission rate can be adjusted.

When selecting brokerage firms, investors should consider factors such as brokerage firms' reputation, service quality, trading software performance, commission rates, and conduct sufficient investigation and comparison. By choosing formal and reliable brokerage firms, investors can better protect their own trading security and legitimate rights and interests.