A full-featured Internet browser, Opera includes pop-up blocking, tabbed browsing, integrated searches, and advanced functions like Opera's groundbreaking E-mail program, RSS Newsfeeds and IRC chat. And because we know that our users have different needs, you can customize the look and content of your Opera browser with a few clicks of the mouse.

Features:

Customize your browser
You can add, remove or reposition buttons and toolbars or change the entire layout of the browser. It is easy to do… or undo.

Access bookmarks instantly
The convenient bookmarks bar keeps commonly visited sites and bookmark folders in front of you at all times, allowing instant access. You can enable this toolbar by selecting Opera menu -> Toolbars -> Bookmarks Bar.
Choose your look and layout
Opera's vibrant user community has created many beautiful skins and setups for you to try, so you can have a customized look for your browser.

Create your own shortcuts
Opera offers many ways to perform browser actions, and you can also customize your own keyboard shortcuts, mouse gestures and more.

Look inside tabs
When you hover the mouse pointer over a tab, a preview shows you the content of that page. When you stack tabs, hovering over a stack also shows a preview of the tabs within, and you may select the tab you want to use.

Re-open tabs you closed
With Closed Tabs, you can open tabs that you accidentally closed or website pop-ups that Opera blocked.

Protect a tab from closing
By right-clicking a tab, you can pin it to prevent it from being closed by accident. Pinned tabs take up minimal space and are automatically moved to the left of other tabs to make them easy to find.
Get a better view of tabs
Visual tabs show a small thumbnail for each website, in addition to the page title and icon. You can drag the tab bar to the desired height to adjust the thumbnail size accordingly.

Save sets of tabs
You can save your open tabs as a "session" and load it later on to open these same pages. You can have multiple sessions and load each one based on what you are doing at a certain time.

And much, much more