SAN FRANCISCO — Apple announced a major new foray into streaming music Monday as it showed off a host of new software features for its iPhones, iPads and Mac computers.

The $10-a-month music service is called Apple Music and combines on-demand listening, a 24/7 radio station hosted by live DJs and a forum for artists to give fans behind-the-scenes content from upcoming releases.

The service, which was announced during Apple’s annual software conference Monday, will be launched this month in more than 100 countries. It comes at a time when iTunes songs and album sales are falling, while streaming music leaders like Spotify and Deezer are gaining subscribers and revenue.

The music service was the biggest news of the company’s five-day conference, but Apple also announced a host of new upgrades and services coming later this year to the operating software for its popular iPhones, iPads and Mac computers.

The new features including enhancements to Siri, the company’s voice-activated digital assistant, as well as Apple Pay, Apple Maps and the Apple Watch. Executives also mentioned a new streaming TV service that Apple is reportedly hoping to announce later this year.

Here’s a look at the new features Apple announced:

APPLE MUSIC

The service represents a chance for Apple to come from behind in a digital music field that it once led. With a lengthy three-month free trial, a $15-a-month plan for up to six family members, and the ability to push the app to hundreds of millions of iPhone and iPad users, the launch could mark a major milestone in digital music.

Besides offering the new subscription plan, the app will continue to allow download purchases from iTunes. It will be available this summer for Apple devices and Windows PCs, and in a break from Apple’s usual practice, it will be released as an app for Android devices this fall.

The live radio station, called “Beats 1,” puts a twist on Internet radio, a field led by Pandora, by having human DJs host a constant stream of talk and music from Los Angeles, New York and London, led by former BBC host Zane Lowe.

The company is also touting a feature called “Connect,” which artists can use to share notes, recordings and photos with their fans who subscribe to Apple Music.

SIRI

Apple’s voice-activated digital assistant will be integrated into the new music service, so subscribers can ask it to play songs from movie soundtracks, find hit songs from a certain year, or create playlists from top songs in different genres.

APPLE PAY

Along with making payments tied to a credit or debit card, Apple Pay will soon incorporate store-issued payment cards and rewards from loyalty programs offered by merchants like Walgreens and Dunkin’ Donuts. That could be a key to making the service more useful for shoppers, according to analysts at Forrester Research.

APPLE WATCH

Apple announced an update to the watch operating system and said it will release the programming tools that independent developers need to build apps that can interact directly with the watch’s hardware and sensors.

The watch still requires a link to the iPhone to perform many functions, but the new software upgrade will let the watch connect directly to Wi-fi networks.