Websites certainly can. It's especially useful when a website has to give out download/install instructions that are specific to each browser. Some sites will then detect the browser and only show the instructions page that is relevant.
This is not an especially common feature because most users already know their browser and can select the correct instructions by themselves.
An user-agent string is a string that the web browser sends out to the web server of the site you're accessing to help identify what operating system and browser you're running in the case the website has a particular configuration that is designed for that particular operating system and browser.
There are various tools to identify various browser issue. Diagnostic tools are used to handle these issues.
YouTube is not a web browser but a website. Web browsers intercept YouTube as a website.
Cookies is a small part of website that is sent to the browser. It improves the performance of the browser.
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Enter the website's URL in your browser's address bar.
A lizard website.
The UCSC browser can be downloaded from the UCSC website under the download section of the website. The download takes about 2 minutes and is installed automatically.
with the interenet
There are many websites dedicated to online or browser games which allows playing games in a browser without downloading and installing a game. Kongregate is a popular website for browser games.
You cannot block sites on Gmail as it is not a browser. You can block sites on browser. Gmail itself is a website running on browser.
The web address that appears in your browser.