User:Pass-authenticated proxies are a type of proxy that provides an additional layer of security and access control by requiring user authentication through a username and password. These proxies are often used in enterprise environments and by individuals who require anonymity and protection of their online activities. By hiding the user's IP address, they can bypass geo-restricted content. 

The format is as follows: IP:PORT:USERNAME:PASSWORD

Benefits

One of the main benefits of user:pass-authenticated proxies is that they can prevent unauthorized access to the internet and limit access to sensitive information, making them a popular choice for enterprises and organizations. These proxies act as intermediaries, just like other proxies, between the user's device and the websites or services they are accessing, providing a layer of anonymity while ensuring that only authorized users can access sensitive data. In contrast, IP-authenticated proxies do not require a username and password for user authentication. Instead, they verify access based on the user's IP address.

Drawbacks

However, user-authenticated proxies can be slower than other types of proxies because each request must be authenticated, delaying access or loading websites. Additionally, they can be more challenging to set up and configure than other types of proxies.

Use-cases

Despite these drawbacks, there are many use cases for user-authenticated proxies, including the bypass of geo-restricted content, for example, for US or EU regions, and the prevention of online tracking. ISPs and other organizations can also benefit from user-authenticated proxies to ensure secure and restricted access to the internet.

Summary

In conclusion, proxies play an essential role in protecting online activities and ensuring secure access to the internet. User-authenticated proxies are valuable for individuals and organizations requiring additional security and access control.