file extension DER

Opera

Opera is a web browser and Internet suite developed by the Opera Software company. Opera handles common Internet-related tasks such as displaying web sites, sending and receiving e-mail messages, managing contacts, IRC online chatting, downloading files via BitTorrent, and reading web feeds. Opera is offered free of charge for personal computers and mobile phones, but for other devices it is not free.

Features of Opera include tabbed browsing, page zooming, mouse gestures, and an integrated download manager. Its security features include built-in phishing and malware protection, strong encryption when browsing secure web sites, and the ability to easily delete private data such as cookies and browsing history by simply clicking a button.

Opera runs on a variety of personal computer operating systems, including Microsoft Windows, Mac OS X, Linux, FreeBSD, and Solaris. Though evaluations of Opera have been largely positive, Opera has captured only a fraction of the worldwide personal computer browser market. It is currently the fourth most widely used web browser for personal computers, behind Internet Explorer, Firefox, and Safari.

Opera has a stronger market share, however, on mobile devices such as mobile phones, smartphones, and personal digital assistants. Editions of Opera are available for devices using the Symbian and Windows Mobile operating systems, as well as Java ME-enabled devices. In fact, approximately 40 million mobile phones have shipped with Opera pre-installed. Furthermore, Opera is the only commercial web browser available for the Nintendo DS and Wii gaming systems. Some television set-top boxes use Opera as well, and Adobe licensed Opera technology for use in the Adobe Creative Suite.

Internet Explorer

Microsoft Internet Explorer is the world most used internet browser.
It provides improved navigation through tabbed browsing, web search right from the toolbar, advanced printing, easy discovery, reading and subscription to RSS feeds, and much more.

Firefox 3

The Web is all about innovation, and Firefox 3 sets the pace with dozens of new features, including the smart location bar, one-click bookmarking and blindingly fast performance.

Mozilla Firefox (abbreviated officially as Fx, but also commonly as FF) is a free web browser descended from the Mozilla Application Suite, managed by the Mozilla Corporation. Firefox had 19.03% of the recorded usage share of web browsers as of June 2008, making it the second-most popular browser in current use worldwide, after Internet Explorer.

Firefox uses the free Gecko layout engine, which implements some current web standards plus a few features which are intended to anticipate likely additions to the standards.

Firefox includes tabbed browsing, a spell checker, incremental find, live bookmarking, a download manager, and an integrated search system that uses the user's desired search engine. Functions can be added through around 2,000 add-ons created by third-party developers,the most popular of which include NoScript (script blocker), Tab Mix Plus (adds many customizable options to tabs), FoxyTunes (controls music players), Adblock Plus (ad blocker), StumbleUpon (website discovery), DownThemAll! (download functions) and Web Developer (web tools).

Firefox runs on various versions of Microsoft Windows, Mac OS X, Linux, and many other Unix-like operating systems. Its current stable release is version 3.0, released on June 17, 2008.Firefox's source code is free software, released under a tri-license GPL/LGPL/MPL.