REDMOND, Wash. — Following plenty of speculation in the past couple of weeks, Microsoft today gave people the first glimpse at its new Internet browser, codenamed Project Spartan.

The demo of the browser on the PC came at an event at Microsoft headquarters that was mainly intended to showcase more of the forthcoming Windows 10 operating system. The browser allows users to mark up websites with text they type in (using a keyboard) or draw (on a tablet with a stylus). The browser also features a reading list to read longer articles in websites and PDFs, Joe Belfiore, corporate vice president of Microsoft’s operating systems group, explained during the demo.

The browser also packs in Cortana. For example, when you’re checking out a restaurant’s website, a Cortana sidebar on the right side of the browser gives you the option to make a reservation. And a quick highlight of an item on a menu on the website can show dietary information in the Cortana sidebar. Sure, you could find that information elsewhere on the Internet, but Cortana’s power in the browser makes things just a little bit simpler, saving you time. And that is, after all, part of the appeal of an assistant.

These new features should arrive for insiders to try out over the next five months, Belfiore said.

The new browser is not entirely meant to replace Microsoft’s longstanding Internet Explorer browser, which dates to the 1990s and competed with Netscape. But this is a new era, with Google’s Chrome and Mozilla’s Firefox enjoying widespread use. Microsoft’s new browser targets them.

At one point in Microsoft’s history, the notion of enabling consumers to use apps on the Internet was not very well accepted. But cofounder Bill Gates in the mid-1990s came to believe that, in fact, the Internet was an essential communication layer. Out came Internet Explorer as an integrated application in Windows, which played to Microsoft’s strength as the leading operating system provider. The association of Windows with Explorer became a key part of antitrust proceedings in subsequent years.

This makes it especially interesting that Microsoft is revealing details about its new browser at the same time that it’s providing new details about its new operating system.

Presumably, Microsoft wants to make a splash today, as it continues to deal with competition from Apple and Google in the mobile platform and browser wars. A new application for surfing the Internet coupled with a new interface for personal computing could have the desired effect.