Anticipation for Apple's (NASDAQ:AAPL) annual Worldwide Developers Conference tends to build in the month's preceding the event. By the time it actually arrives the rumors in circulation range from the plausible to the utterly preposterous.

Will the company announce a new music service? Is it introducing a new Apple TV? Will it have a subscription TV service? Will CEO Tim Cook reveal himself to be a robot?  All of those ideas (well, not the last one) and many more have been floated in advance of the event.

As the company kicked off WWDC 2015 Monday with a keynote address led by Cook, anticipation was high. Apple did not disappoint, though it also did not deliver on every rumor or expected announcement.

The theater for the keynote holds 6,000 people. This is the line to get in. Source: Apple.

New Mac OS and Safari features are coming
After an amusing video starring Bill Hader, various app characters (including an Angry Bird), and a number of cameos, Cook took the stage to rock star-like applause. After welcoming the crowd and telling a brief baseball story, he jumped right into OS X.

"We're bringing a whole bunch of new great capabilities to the Macintosh," Cook said before bringing Apple executive Craig Federighi to the stage to talk about the operating system. Federighi told the crowd the new version of the OS would be called El Capitan.

"We focused on two major areas; experience and performance," he said. This includes improving how windows are managed on the system, adding real-language search features, and making it easier to locate your cursor with a simple shake when the screen wakes up. The new OS also includes an enhanced version of the Safari browser that offers a new form of bookmarking called "pinned" sites.

"We've optimized performance throughout the system," Federighi said before announcing that Metal -- a system that improves graphic speeds and has been used on iOS for iPhone and iPad -- would be coming the Mac. "Metal combines the computing power of OpenCL and the graphics power of OpenGL in a high-performance API that does both," he added.

That might mean little to regular users, but it should make graphics render fast, which should be exciting for game developers.

El Capitan has been made available to developers and will be released as a free upgrade in the fall.
Siri has become pretty accurate, and now it's getting more features
Apple's voice assistant Siri now handles over 1 billion requests per week and is "down to a 5% error rate," according to Federighi. That's a 40% improvement over last year. Continuing the improvement and making it a proactive assistant will be the goals of the latest updates.
That means that Siri will have greater situational awareness (it will know when you are in the car, for example) and it will work with plain language ("remind me of this when I get home"). Siri will also be able to interact with apps, and it will know when you do something like plug in a pair of headphones.
All of these features are done on-device and no personal information is shared with Apple in order to protect privacy. None of the info is shared with third parties.
Apple Pay is getting bigger
Apple Senior Vice President Jennifer Bailey took the stage to announce that Discover (NYSE:DFS) would be integrated into Apple Pay. She added that a number of new retailers are coming on board, including major players such as Trader Joe's and J.C. Penney. 
Bailey also announced that Apple Pay would launch in the United Kingdom next month in over 250,000 locations. She noted that Passbook would be renamed "Wallet" and a number of companies would be integrating their store and loyalty cards into the system.
"We're well on our way to replacing the wallet," she said.
The News app is coming
Apple introduced a new "News" app that creates a custom content experience from a number of top partners. Users can create a personalized feed that gives them "all of their news in one place," said Apple Vice President Susan Prescott.
It's not all that dissimilar from Flipboard or a number of other new apps. "New is smart, so the more I read, the better it gets," Prescott said. The app also has an "explore" feature that helps users discover new content.
Apple did not announce a release date for the app, but it was made clear that, much like the new Siri features, it does not store any personal data or share it with third parties.
iPad will add multitaking, better battery management
iOS 9 will offer true multitasking on the iPad for the first time. Apple created a new "task switcher" to allow sliding between apps with a finger touch. The new system allows for split-view use of multiple apps at the same time.
Full multitasking will only be offered on the iPad Air 2, the highest-end model of the tablet.
Apple also announced a new single-button way to put your iPad into low-battery mode. This could allow the tablet to operate for up to three extra hours without the user having to guess at what features to turn off to maximize battery life.
Apple's Swift is going open source
In an unprecedented move for the company (which has always kept everything it owns proprietary) Federighi announced that its programming language, Swift, would become open source by the end of the year. That announcement was met with explosive applause that blew away any other reaction at the event.
Here comes Apple Music
Cook took the stage back to close the keynote and announced that the company has "one more thing." He introduced a video about the history of music as a prelude to announcing Apple's new Music service.
"Today we're announcing Apple Music, the next chapter in music," he said before bringing Jimmy Iovine to the stage.
He introduced a video that laid out some of the details of the new service. The video talked about respecting music as art and being for both major players and small artists "in their bedrooms."
Apple Music allows subscribers to stream all its music on iTunes. It also has playlists and Apple's Beats 1 programmed radio station. Apple Music will work through the music app on iPhones and other Apple platforms.
Iovine spoke at length about human-curated playlists before hyping Beats 1, which he called the first-ever worldwide live music station. He said the channel would play music not based on data, "only music that feels great and sounds great," he said.
The service also features Connect, which allows established, unsigned, and new artists to all share music "on the biggest platform in the world." It's basically an invitation for artists to drop their record labels and simply distribute music through Apple.

Apple will give users a free three-month membership, after which it will charge $9.99 a month for a subscription. There will also be a family plan providing service for up to six family members for $14.99 a month.

Apple Music launches on iPhone, iPad, iPod touch, Mac and PCs starting June 30. It will come to Apple TV and Android phones this fall.