Many behind-the-scenes actions give you instant results whenever you enter a query in a browser’s search bar. A “user agent” is one of these actions which connects your browser to the website.
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A user agent is a string of text that identifies and connects your browser to the web server. Your browser familiarizes itself with the web server through a user agent. Take it as your web browser, greeting the server with “Hello, web browser here.” The web server then utilizes this information and caters to different web pages, operating systems, or browsers.
Understanding everything about user agents is crucial if you are web scraping. This article will help you learn more about what a user agent is in the browser, the most common user agents, how to change a user agent, and the best solution for web scraping.
What Is a User Agent?
User agent refers to any software that establishes an interaction between end-user and web content. Simply put, it connects the user with the internet.
When a browser communicates with a website, it has a separate user agent field in the HTTP header. The content in the user agent field introduces the browser to the server, so it is unique for every web browser. This means every browser has a unique user agent.
A user agent string, or UA string, is a line of text that the client computer software sends upon a request. This string helps the web server identify the type of device, browser, and operating system the request is coming from.
For instance, the web server can detect that you’re using the Firefox browser on Windows 10 on your PC. After the identification, the web server uses this information and gives a suitable response according to the type of browser, device, and OS used.
Some most common user agent examples include:
- Web browser
- Gaming consoles
- SEO tools
- Legacy operating systems
- Link checkers
- Web applications, including PDF readers, video players, and streaming apps
While humans can manage some user agents, others are controlled automatically by their respective websites. Search engine crawlers are one such example.
The Importance of User Agents in Web Scraping
It’s essential to understand user agents because they distinguish between different browsers. When a web server identifies a user agent, it starts negotiating with the browser for the content display. This process is the HTTP mechanism that enables you to provide different resource versions through a similar URL.
When you search a website URL, the web server checks the user agent and gives you the appropriate webpage results. Therefore, you don’t have to enter different URLs for every device you’re trying to access a particular device. Instead, the same URL will show you the appropriate versions of a webpage according to your device.
Understanding the content negotiation of user agents is vital for image format display.
For example, an image is generally shown in PNG, JPG, and GIF formats. However, older versions of MS Internet Explorer don’t support PNG images, so they display GIF versions to the users. Similarly, modern browsers display pictures in most formats, especially PNG and JPG formats.
For instance, a video player allows you to stream videos, and a PDF reader lets you access PDF documents only, not MS Word files. The PDF reader doesn’t identify the MS Word Document’s information.
When it comes to web scraping, business professionals use “user agent switching,” which refers to changing your user agent per your requirements. There are numerous user agents, with each agent communicating different messages to the website’s browser that you’ll try to scrape.
Some websites even block specific user agents, so it’s essential to understand which user agent you should use, when, and why.
The Most Common User Agents List
The web server uses the information collected via user agents to perform specific tasks. For example, a website can transmit desktop pages to desktop browsers by using this information. It can also notify the older version of Internet Explorer about an upgrade.
The user agent header format for Firefox on Windows 7 is:
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0) Gecko/20100101 Firefox/12.0
By observing the user agent “Mozilla/5.0”, you can see that it has a lot of information for the webserver. This includes Windows 7 operating system, code WOW64 indicating that the browser is running on a Windows 64-bit version, the code name Windows NT 6.1, and the browser name Firefox 12.
Here are some most common user agents:
- Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36
- Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:53.0) Gecko/20100101 Firefox/53.0
- Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.0; Trident/5.0; Trident/5.0)
- Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Trident/6.0; MDDCJS)
- Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.79 Safari/537.36 Edge/14.14393
- Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)
You can use it rather than opting for a user agent switcher if you want to imitate another browser.
Use Cases for User Agents
Some everyday use cases for user agents include:
Web scraping helps businesses keep an eye on their competitors’ performance and extract relevant data from their websites to make informed decisions. Unfortunately, many websites tend to block web scraping tools by restricting requests from user agents not belonging to the primary browsers.
When the user agent is identical during web scraping, the web server identifies such requests as suspicious. This is why changing user agents is crucial for web scrapers.
Price scraping is a type of web scraping that helps e-commerce businesses to track their competitors’ websites to know their products’ real-time selling prices.
User agents work the same way for price scraping as they do with web scraping. So, user agent switching and upgrading is essential for businesses to scrape their competitors; web for a long time.
Fingerprinting is the process of collecting information about a device for identification. The scripting languages at the client’s site enable the collection of fingerprints, such as types and versions of browsers and operating systems, fonts, plugins, screen resolution, camera, microphone, etc.
Fingerprinting also collects user agent headers when the connection is established between the website and the server.
Serving web pages
A web server determines the web pages it must serve to a web browser by looking at the user agent information. While some web pages only serve older browsers, others are suitable for modern ones. Because of the difference in the user agent, you’re most likely to see “This web page must be viewed in Google Chrome.”
Suitable operating systems
User agents also help web servers identify which content must be served to every operating system. Due to different user agents, you see varying web page versions on your mobile phone screen and desktop.
Web servers also use user agents to acquire information or statistics about the most-used operating systems and browsers. For example, this is how you know Chrome is more prevalent among users than Safari or any other counterpart.
Web crawling bots
Web crawling bots also use user agents to access different sites. If you adjust your user agent similar to the search engine’s bot, you can even penetrate the registration screens without even registering.
The web server detects the bots through unique user agent strings mentioned in the robots.txt file.
Many browsers also allow you to set a custom user agent. This way, you can see how the web servers display a web page on mobile devices and desktops.
How Custom User Agents Help You Avoid Bans While Web Scraping
When web scraping competitors’ sites, you need to ensure that you don’t get banned or blocked. One precautionary measure is changing, rotating, or switching your user agent.
Every website receives thousands of requests daily. It identifies the web browser and the OS of each request through its user agent. If a website gets loads of requests with the same user agent, it’ll probably assume you are suspicious and block you.
This is why a business needs to change the user agent string frequently instead of using one. You can also use fake user agents in the HTTP header to prevent the ban or use proxies to shield your IP address. Blazing SEO has the best residential, ISP, and data center proxies for web scraping.
Many web scrapers also change their user agent settings to that of popular search engines. Since most websites want to rank well on search engines, they sometimes let the browser welcome such user agents without banning them.
Scraping Robot: A Hassle-Free Web Scraping Solution
User agents establish a connection between your web browser and the webserver. Because of this connection, your web browser gives you accurate results whenever you search for a query. The process happens after analyzing the type of your device, browser, and operating system’s version.
Many websites have crawlers that track every activity, causing a major issue for web scrapers. Yes, you can lower the risks of being blocked if you change browser identification for every request. However, the process can become quite time-consuming and tedious, especially if you deal with loads of daily web scraping work.
That’s when you might need Scraping Robot to make things a little easier. The experts at Scraping Robot build customized scraping solutions according to your needs and budget. No more blocks, captchas, proxy management, or browser scaling! You can give your web scraping worries to Scraping Robot and focus on the things that really matter.
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