A user agent is a computer program representing a person, for example, a browser in a Web context.
Besides a browser, a user agent could be a bot scraping webpages, a download manager, or another app accessing the Web. Along with each request they make to the server, browsers include a self-identifying User-Agent HTTP header called a user agent (UA) string. This string often identifies the browser, its version number, and its host operating system.
Spam bots, download managers, and some browsers often send a fake UA string to announce themselves as a different client. This is known as user agent spoofing.
A typical user agent string looks like this: "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:35.0) Gecko/20100101 Firefox/35.0".
There is protection in place to stop the scraping of these user agent listings. We've had to do this because otherwise we get constantly overrun by inconsiderate or malfunctioning bots which overload the system.
As such, we're forced to block traffic from popular web hosting companies, VPNs and Proxies, we also rate limit requests and have some other checks too. If you need to get access to the listings of user agents you can either get them in an easy-to-use database download or via the API.
Rv: gecko version indicates the release version of Gecko (such as 17.0 “). The Chrome (or Chromium/Blink-based engines) user agent string is similar to Firefox’s.
For compatibility, it adds strings like HTML, like Gecko and Safari. The Opera browser is also based on the Blink engine, which is why it almost looks the same, but adds “Or/< version >”.
In this example, the user agent string is mobile Safari ’s version. During authentication flow in Safari, we have a case when in order to satisfy a condition policy, user needs to install the app on his device.
Safari Preferences Security Plug-in settings On the left-hand side, tick ‘Java’ and select the website you wish to enable it on (in this case, I’m guessing ‘ exams2score.com or something similar).
Ensure that you have ‘Internet Explorer 11’ selected from the ‘ User agent section of the ‘Develop’ menu. Go back to the website you wish to use Internet Explorer and Java on, and refresh the page.
“Crawler” is a generic term for any program (such as a robot or spider) that is used to automatically discover and scan websites by following links from one webpage to another. This table lists information about the common Google crawlers you may see in your referrer logs, and how they should be specified in robots.txt, the robots meta tags, and the X-Robots-Tag HTTP directives.
Some pages use multiple robots meta tags to specify directives for different crawlers, like this: In some circumstances you may want to identify which device and/or browser your respondents are using to answer your consultation.
The user agent field is often deliberately obfuscated to discourage feature detection and even then can vary depending on the installed plugins. The 'Browser Name' section of the MDN Web Docs article on Browser detection using the user agent is a reasonably good reference, which we have paraphrased below.
The table below is copied from there, and is a rough guide to recognizing browser and version from user agent values: If in doubt, doing a Google search for the full user agent (in quotes) will almost always bring something up that will tell you what browser it is.
Armed with this information, you can develop richer and more dynamic websites that deliver different experiences based on the user agent that's visiting. User agents are also critical in controlling search engine robots using the robots.txt file on your server.
In order to leverage this information, you need to understand the component parts of an user agent string and consider also the potential risks of using this method to deliver content. It's easiest to understand user agents if we backtrack and look at the evolution of the web.
When the internet was a text-based system, right back at the beginning of its use, users had to type commands to navigate and send messages. We simply point and click, and the browser is acting as our agent,” turning our actions into commands.
Browsers : Including Microsoft Edge, Internet Explorer, Firefox, Safari, Chrome, BlackBerry, Opera, Opera Mini, iOS Safari, Chrome for Android, Samsung Internet, HQ browser, and others. Plus a whole range of feed readers, validators, cloud platforms, media players, email libraries, and scripts.
Once the user agent has identified itself to the web server, a process called content negotiation can begin. This allows the website to serve different versions of itself, based on the user agent string.
The user agent application is Mozilla version 5.0, or a piece of software compatible with it. That's because Internet Explorer originally had to declare itself to be Mozilla compatible in order to receive content with frames.
Overall, we can empower our scripts to make the best choice for our visitors, based on their user agent. More, we can feed that data back into a cycle of continuous improvement, analytics and other processes, like conversion optimization.
Chrome Review (Lollipop and above) Mozilla/5.0 (Linux; Android 5.1.1; Nexus 5 Build/LMY48B; WV) Apple WebKit/537.36 (HTML, like Gecko) Version /4.0 Chrome/43.0.2357.65 Mobile Safari /537.36 An user agent is a particular string of characters in each browser that allows acts as an identification agent.
The user agent allows the web-server ti to identify the operating system and the browser. The user agent string contains the user application or software, the operating system (and their versions), the web client, the web client's version, and the engine responsible for the content display (such as Apple WebKit).
It is a rendering engine that processes HTML and CSS to interpret and present web pages. WebKit is also responsible for allowing you to navigate through links on a web page.