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".
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So, to get info about your browser, websites often examine the ‘ user agent ’, or ‘UA’ string. An user agent (UA) string is able to be used to detect what version of a specific browser is being used on a certain operating system.
Mapping UA string tokens to a more human-readable browser name for use in code is a common pattern on the web today. When mapping the new Edge token to a browser name, Microsoft recommends using a different name than the one developer used for the legacy version of Microsoft Edge to avoid accidentally applying any legacy workarounds that are not applicable to Chromium-based browsers.
When Microsoft is notified about these types of issues, website owners are contacted and informed about the updated UA. In these cases, Microsoft uses a list of UA overrides in our Beta and Stable channels to maximize compatibility for users who access these sites.
navigator.sergeant : This method reads the navigator object when the page load is finished. navigator.sergeant : This method clones the “navigator” object exactly when page is about to render to prevent any external scripts from altering it later.
Tab : Could be one of “navigator”, “UA_prayer”, “platform_JS” which indicates the default rendering engine that is used to display the results. Verbose : Could be one of “true” or “false” values which indicates whether the page uses all methods or just the active one.
User agents are the strings of text which specify the browser and operating system of web servers. User agents are present in HTTP headers when the browser wants to communicate with a server.
Each browser has its specific useragentstring and web servers utilize this information to deliver appropriate material across different operating systems. An example of this is the mobile version of webpages in devices; usually slimmed down and organized vertically for user ease.
Web servers provide the bots with special treatments and verifications such as mandatory registrations, screens, etc. Mozilla was considerably more advanced in terms of connectivity and security than Mosaic because of the ease of supported frames it provided.
This was a remarkable advancement considering the other browsers made use of sending old pages without any frames at all. However, there was still no receiving end of webpages with frames, because they were just shared with Mozilla browsers.
Essentially, an user agent is a way for a browser to say “Hi, I’m Mozilla Firefox on Windows” or “Hi, I’m Safari on an iPhone” to a web server. The useragentstring identifies the browser as IE 9 with the Trident 5 rendering engine.
The plot thickens: Chrome is pretending to be both Mozilla and Safari. To understand why, we’ll have to examine the history of user agents and browsers.
(Yes, this means that you can sometimes bypass registration screens by setting your user agent to Google bot.) He's written about technology for nearly a decade and was a World columnist for two years.
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The landscape of mobile browsers is quite complex, with several major players (pre-installed in most cases) and a number of locally popular contenders. While all phones come with pre-installed browsers, both Google Play and Apple App Store offer a number of alternative browsers, some focusing on speed and lightness, others on saving bandwidth and blocking ads, and an ever-increasing amount claiming to increase privacy and reduce a users' mobile digital footprint.
A simple regex solution searching for keywords will struggle in terms of accuracy and detection speed. It offers a patented algorithm that detects and identifies all devices requesting online content through parsing UA strings based on a constantly updated, massive list of connected devices.
WebKit (18,642,786) Blink (9,913,314) Trident (1,737,329) Presto (368,303) Gecko (299,203) Edge HTML (25,016) Gonna (3,639) HTML (3,483) Seafront (3,419) If you need to integrate the user agent parser directly into your website or system then it's very simple to use the API.
They reveal a catalog of technical data about the device and software that the visitor is using. 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 useragentstring and consider also the potential risks of using this method to deliver content.
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.
This is a really set of data for web developers since it allows them to customize the experience depending on the user agent that's loaded the page. Browsers are a straightforward example of an user agent, but other tools can act as agents.
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.
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.
More, we can feed that data back into a cycle of continuous improvement, analytics and other processes, like conversion optimization. As we mentioned in the introduction, search engine crawlers are a very specific type of user agent.
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.