Proxy Servers 101: How They Work and When to Use Them

A proxy server is a system that handles internet traffic on behalf of users. It receives requests, applies any configured rules, and then forwards those requests to the intended destination. Because it has its own IP address and resources, it can process, log, filter, or cache traffic at scale.

If you're learning about or working with proxy servers, it's crucial to understand them without misconceptions. We’ve created this guide to explain how proxy servers work, classify them, and explain their benefits. It also includes insights on free proxy servers and choosing the right proxy server, so you’re all covered.

How Do Proxy Servers Work?

When a device makes a request, it first goes to the proxy server rather than to the destination. Once received, it is examined according to the set rules, and the request is then allowed, modified, cached, or forwarded to the destination.

If the request is forwarded, the proxy sends the request and its information to the target server. To the destination, the request looks like it was sent by the proxy's IP address and not by the original device, masking the original client IP address.

When the target server responds, it is sent back to the proxy. The proxy may log the action, scan the content to identify risks, or even compress the data. Sometimes, it will also store the responses in a local cache to make future requests faster.

Lastly, the processed response is sent back to the device. To the user, everything feels direct, but it's the proxy server in the background adding layers of privacy and control along the way.

Types of Proxy Servers

When learning about proxy server types, arguably most wonder, “Are all proxy servers the same, or are there different kinds?” The confusion comes from the fact that while there are only a few true categories, even small variations are often presented as entirely separate types.

To get over it, the best way to understand proxy server types is to consider the architectural level first. Broadly, they fall into two main groups: forward proxies and reverse proxies.

Forward Proxies

A forward proxy works on the client's side. All client requests go through it before reaching external servers. To the servers, it looks like the request came from the proxy itself, not the original device.

It gives control over what traffic leaves the network and what information is shared. Hence, forward proxies are widely used when client details need to be hidden, access rules applied, or traffic leaving an organization managed.

Reverse Proxies

A reverse proxy works on the server's side. Instead of handling traffic going out, it manages traffic coming in. When users on the internet try to connect, their requests stop at the reverse proxy first. The proxy then decides which backend server should handle the request.

Reverse proxies allow servers to distribute traffic, hide backend details, and handle more connections efficiently. As a result, they are often preferred for load balancing, SSL termination, caching, etc.

Find it confusing? Here’s a simple table that clears it all.

Classifying Proxy Servers

What is often presented as separate proxy “types” are either variations or configurations of forward proxies. As reverse proxies are less common, let’s shift our focus to forward proxies. Let’s classify them accordingly and debunk the misconception of different proxy types.

By Anonymity

• Transparent Proxy Servers: They forward requests without hiding the client’s IP address. They are mainly used where anonymity is not important. The catch is that they are easy to detect, so they aren’t preferred for privacy-based tasks.
• Anonymous Proxy Servers: The client’s IP address is hidden, but it identifies itself as a proxy. In terms of protection, it is considered a step above transparent proxies. However, the letdown is that it cannot fully mask activity, except for basic privacy.
• High Anonymity Proxy Servers: Often called elite proxies, these hide both the client’s IP and the fact that a proxy is being used. They are harder to detect and provide stronger privacy compared to other anonymity levels. Many of the best proxy servers fall into this category.

By Infrastructure

• Datacenter Proxy Servers: The proxies are hosted on servers in data centers and use IP addresses provided by those centers and not ISPs. They are fast, affordable, and widely used for bulk tasks. However, they are easier to detect, which is why many buy proxy servers only for large-scale projects where detection isn’t an issue.
• Residential Proxy Servers: They use IP addresses assigned by ISPs or real households. As a result, the traffic appears genuine, making it harder to block. While reliable and capable, the price is on the higher side. Regardless, many choose to buy them as they’re a great choice for handling sensitive tasks.

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By Access Model

• Shared Proxy Servers: These are used by multiple users simultaneously. While cheaper than private options, they are often slower and a privacy concern. Many cheap proxy servers fall into this category because costs are divided among users.
• Rotating Proxy Servers: Each time a connection is made, the user is assigned a new IP address from a pool. This makes them highly effective because requests appear to come from different users. Many prefer rotating residential proxy servers as they’re great for reliable and stable performance.
• Public Proxy Servers: They are free and open for anyone to use. While they may sound attractive, most free proxy servers come with serious risks, such as poor performance, logging, or even malware. We don’t recommend it for any, even in a sandbox environment.
• Private Proxy Servers: These are also known as dedicated or personal proxy servers. They are dedicated to a single user and not shared with others. Experience better speed, reliability, and security than shared or public options, but at an added expense. Many buy proxy servers in private form when performance and privacy are a priority.

By Protocol

• HTTP Proxy Servers: They process and forward unencrypted web traffic. As data isn’t secured, information like logins or personal details can be intercepted if used on public networks. Hence, they are mostly used for non-sensitive browsing or caching content.
• HTTPS Proxy Servers: These are an upgrade over HTTP because they support encrypted web traffic. They use SSL/TLS to keep communication private and prevent eavesdropping, making them a safer choice, especially when handling sensitive information.
• SSL Proxy Servers: A broader category that handles any traffic secured with SSL/TLS, not just web pages. While HTTPS proxies focus only on web traffic, SSL proxies can also secure protocols like FTPS, SMTPS, or IMAPS. In practice, the terms SSL and HTTPS proxy are often used interchangeably since most encrypted traffic online is HTTPS.
• SOCKS Proxy Servers: Works at a lower level, forwarding traffic without inspecting it. SOCKS4 is limited to TCP traffic and lacks authentication, which makes it simple but restricted. SOCKS5 adds support for TCP and UDP, multiple address formats (IPv4, IPv6, domains), and authentication.

Want to learn more about SOCKS proxies? Check out: What Is a SOCKS Proxy? The Simple Guide That Clears It Up

What Are the Best Proxy Servers?

There isn’t a best proxy server, and the best one is always the one that fits your needs. The strength of forward proxies is that they can be combined through proxy chaining, creating an ultimate proxy server.

Here’s a quick breakdown of popular combinations:

Note: While proxy chaining unlocks benefits, the biggest downsides are the complexity, latency, and overall price. Also, if a proxy server breaks, the entire chain breaks, so stability is also a concern if it is not configured correctly.

How to Choose the Right Proxy Server?

Now that you’re aware of different proxy server types and possible combinations, the final step is knowing how to choose the right one. Use the suggestions below to your advantage by considering them as a checklist:

• Work only with providers that are transparent about their service and policies.
• Avoid free proxy server lists as they often come with hidden risks.
• Choose based on your real need, not just what sounds popular.
• Check the size and diversity of the IP pool offered.
• Think about scalability for future growth, not just your current project.
• Balance cost with quality, avoid unreliable proxy servers that fail under load.
• Look for global coverage if location targeting is important to you.
• Make sure the proxy is easy to set up and works well with your tools.
• Test before you commit long-term, so you know what you are getting.
• Verify legal compliance if you plan to buy proxy servers for business use.
• Watch out for hidden limits like capped requests or restricted endpoints.
• Read independent reviews or case studies to see how others rate the service.
• Only buy proxies from providers that update and maintain their pools actively.
• Compare different providers side by side instead of rushing into one choice.