captchas是什么意思 captchas的读音、翻译、用法

1. 定义及起源：'captchas'是指在计算机上使用的一种用于确定用户是否为人类的检测机制。其全称是“Completely Automated Public Turing test to tell Computers and Humans Apart”，即完全自动公开图灵测试，旨在防止恶意软件和计算机程序使用自动方式破解密码等。它的起源可追溯到20世纪90年代早期，当时它被称为“图像验证码”。

例句：

- Captchas are used on websites to ensure that the user is a human and not a spam bot.

- The purpose of captchas is to prevent automated attacks and increase security.

- The most common type of captchas requires the user to type in a series of distorted letters and numbers.

- Captchas have become more complex over time as spammers and hackers have found ways to bypass them.

2. 类型：目前，常见的captchas主要有文字、图像、音频、数学等类型。其中，文字和图像类型是最常用的，它们通常要求用户识别并输入一些歪曲的字母、数字或图片中的物体等。

例句：

- This website uses a text captcha to verify that the user is a human.

- Some captchas require users to identify common objects such as traffic lights or storefronts.

- Audio captchas are used for visually impaired users who cannot see the images or text on the screen.

- Math captchas require users to solve a simple math problem, such as addition or subtraction.

3. 应用范围：captchas被广泛应用于互联网上，特别是在登录、注册、评论、投票等活动中，以确保只有真正的用户才能访问或参与。captchas也被用于防止DDoS攻击、爬虫、垃圾邮件等。

例句：

- Users must enter a captcha to register for this website.

- A captcha is required to leave a comment on this blog post.

- This online poll uses captchas to prevent multiple votes from the same person.

- Captchas are used to protect websites from automated attacks and spam.

4. 问题和挑战：虽然captchas是一种有效的身份验证工具，但它们也存在一些问题和挑战。例如，captchas可能会对老年人、视觉障碍者和非英语母语者造成困难；一些网站可能需要用户在过于频繁的情况下输入captchas，这可能会使他们感到不便或烦恼；一些恶意软件和计算机程序已经成功地绕过了某些类型的captchas，这使得它们变得不那么可靠。

例句：

- Some users find captchas difficult to read or understand, especially if they are visually impaired or don't speak English.

- Some websites require users to enter captchas too frequently, which can be annoying or frustrating.

- Hackers have developed methods to bypass certain types of captchas, which reduces their effectiveness as a security measure.

- Captchas can be a barrier to entry for some users, which can limit their access to online services.