> For the complete documentation index, see [llms.txt](https://docs.marsproxies.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.marsproxies.com/marsproxies-documentation/overview/residential-proxies/proxy.md).

# Proxy

This section walks you through building and configuring a proxy string. You'll learn how to target specific locations, set up rotation preferences, choose the right protocol, and more. We'll also show you how to make a request using your proxy.

First, it helps to know that every proxy string is made up of four components: **host**, **port**, **username**, and **password**. These can be arranged in different ways, but throughout this documentation we'll use the following format: `HOST:PORT:USERNAME:PASSWORD`.

With residential proxies, the **password** field does more than just authenticate — it's also where you define your proxy configuration settings (such as location targeting and rotation behavior).

Here's an example proxy string configured to target the state of Texas in the USA:

```
ultra.marsproxies.com:44443:username123:password123_country-us_state-texas
```

Breaking this down, the string consists of four colon-separated sections:

* **Host** — `ultra.marsproxies.com` — the proxy server address you connect to
* **Port** — `44443` — the port number used for the connection
* **Username** — `username123` — your account username
* **Password** — `password123_country-us_state-texas` — your base password followed by configuration parameters

The **password section** is where all proxy settings are appended. Configuration parameters are added directly after your password using an underscore (`_`) as a separator. In the example above, `_country-us` specifies the target country (United States) and `_state-texas` narrows it down to the state of Texas.

The following pages cover each available configuration option in detail.