Just a few days after it released OS X Yosemite, the latest version of its operating system for the Mac, Apple is making a major update to its mobile operating system available for download Monday, with new features including Apple Pay and improved performance for older devices. It also comes with the Continuity feature, changes to the way iOS stores photos in the cloud and the ability to use the iPhone as a hotspot.

Monday's release of iOS 8.1, first announced Thursday at Apple's media event unveiling new iPad and iMac models, comes on the heels of the rocky September launch of iOS 8.0. Users reported problems with that update including problems running in landscape mode, inability to connect to Bluetooth devices and loss of cellular service, ultimately forcing Cupertino to scramble to release an interim fix days later.

Apple Pay

One of the most anticipated new features included in the iOS 8.1 update is Apple Pay, first announced at Apple's September keynote in which it introduced the iPhone 6 and 6 Plus, alongside the Apple Watch. With Apple Pay, users will be able to securely store their credit card information on their iOS device, which they can then use to make in-store payments.

However, although the latest operating system will be compatible with the iPhone 4s model, users will need the iPhone 6 or 6 Plus to make use of the payment service. Models in the iPhone 5 line will eventually be able to make use of the payment service next year, if they are paired with the Apple Watch.

The update also introduces a suite of features collectively known as Connectivity. One such feature, Instant Hotspot, lets an iOS device act as a Wi-Fi hotspot to share its Internet connection with other Apple devices. Another Continuity feature, SMS Relay, lets users use their Macs to send and receive SMS and iMessages, or to continue conversations begun on one device on another. Several of the Continuity features first appeared last week when Apple pushed out the latest version of its desktop and laptop operating system Yosemite.

Improved Performance

The iCloud Photo Library, which replaces Photo Stream, is another hotly anticipated new feature. The service allows users to upload photos and videos directly to their iCloud accounts, rather than store them locally on their devices. And Camera Roll, the popular way to view photos taken with the iPhone that Apple discontinued with iOS 8.0, makes its triumphant return after a massive outcry by iPhone users.

Apple also is promising iOS 8.1 will be easier to run on older iPhone models, such as the 4s or iPad 2. Although the new system was ostensibly compatible with those devices, several media outlets urged users to avoid upgrading to iOS 8.0 when it first launched, thanks to reports that the system ran intolerably slow on older processors.