中文：

U盾，全称为USB Key，是网上银行常用的安全工具，也被称为数字证书或USB Key证书。它是一种用于网上银行电子签名和数字认证的智能芯片，可以保证网上交易的安全性和真实性。

U盾的外观类似于一个U盘，通常由塑料或金属制成，内置智能芯片，具有高度安全性和稳定性。当您使用网上银行进行转账、支付或其他交易时，需要使用U盾进行电子签名，以确保交易的安全性和真实性。

使用U盾非常简单，只需将其插入计算机的USB接口，然后输入密码即可进行电子签名。与传统的纸质签名相比，使用U盾进行电子签名更加方便、快捷、安全。同时，U盾还可以保护您的账户信息和资金安全，避免遭受黑客攻击和欺诈行为。

总之，U盾是网上银行用户必备的安全工具，可以有效地保护您的网上交易安全和资金安全。如果您需要进行网上交易或使用网上银行，建议购买一个可靠的U盾，以确保您的交易安全和账户安全。

英文：

USB Key, also known as USB smart card or digital certificate, is a commonly used security tool for online banking. It is a smart chip used for electronic signature and digital certification in online banking to ensure the security and authenticity of online transactions.

The appearance of USB Key is similar to that of a USB flash drive, usually made of plastic or metal, and built-in smart chip, with high security and stability. When you use online banking for转账、payment or other transactions, you need to use USB Key for electronic signature to ensure the security and authenticity of the transaction.

Using USB Key is very simple, just insert it into the USB interface of your computer, and enter the password for electronic signature. Compared with traditional paper signatures, using USB Key for electronic signature is more convenient, fast, and safe. At the same time, USB Key can also protect your account information and fund security, avoiding hackers and fraud.

In summary, USB Key is an essential security tool for online banking users to effectively protect the security of your online transactions and fund security. If you need to perform online transactions or use online banking, it is recommended to purchase a reliable USB Key to ensure the security of your transactions and account security.