At my university, a friend decided to learn to be a disc jockey, for fun. She was talented, learned fast and became one of my university's most popular D.J.'s. If I had tried to learn that skill, it would have taken me a long time, I know. But the world has advanced and your smartphone and tablet can manage a lot of the tasks of mixing music for you -- whether you're a real D.J. or just a musical amateur keen to liven up a party.
Djay 2 by Algoriddim is perhaps the most full-featured D.J. app available, which is probably why it costs $9.99 for iPad. The app plays MP3 tracks stored on your device but with a traditional D.J.-ing vibe: Its main display looks like a classic twin record deck. When you load a track on one of the decks the album art is displayed in the middle, and while it's playing the art even spins like a record. To extend this realistic look, you can "scratch" this record by swiping your finger, as if it were the real thing.
Manually mixing from one track to the next is as easy as pressing play on the second deck's play button as the first one begins to end. Then you slide the fader control across so the first track becomes quieter and the second louder, as on a real mixing desk.
But this app does much more. Tapping on the "sync" button aligns the playback speed of two tracks to match each other so there's no awkward change in the rhythm. And for a different interface, the app can show you the music as a scrolling sound wave. There are also straightforward controls for creating playlists or adding special audio effects like distortions.
Djay 2 is jammed with features, but you don't have to use them. You can simply use it to manually play tracks one after the other, or you can push the "automix" button. Here the app looks at your available music and automatically plays suitable tracks one after the other, even fading between them when it's time.
Completely amateur D.J.'s may initially find themselves at a loss because of this app's complexity. But its controls are clear, and there is a help menu.
A similar full-featured app is Edjing, which is free on Android, iOS and for Windows 8 machines. It is similar to Djay 2 and has the same visual display of two record decks, but it's simpler to navigate. It also has special effects, but you have to acquire them in the app by paying with vinyl "tokens," which you have to buy. For example, to add a cool phaser effect you need 10,000 tokens, which could cost you up to $10. You can earn more tokens by sharing your mixes online or signing the app up to Facebook.
The app may be less daunting for beginners than some of its peers, and it also has an "automix" button for simplicity. But you may find the app limiting as your skills improve, and the token system could irritate you.
Traktor DJ on iPad has an interface that shows you the music you're mixing as waveforms on a colorful graph display. The rest of the controls, which include special audio effects and the ability to set loops and so on, are also simply displayed. Traktor also has a sort of automatic detection system for your music so you can mix one track seamlessly into an appropriate follow-up track. . But it's best for those who prefer an unfussy control interface, and it's expensive at $19.99.
On Android, an alternative is DJ Studio 5. This app looks like a simpler Edjing, complete with twin record decks. But it is full of features, with several built-in special effects, automatic tempo syncing and the ability to build an "automix" playlist of your music. Incredibly, it's free, but the interface and controls can be confusing to navigate.
For an infinitely simpler, beginner-friendly D.J. app there's the Party Monster, $2 on iOS. This app is not about automixing tracks with similar tempos or spinning faux record decks. Party Monster simply lets you build a playlist of music for a party through a simple touch interface. It lists your available music, and then you swipe the tracks you want into the "to be played" list. Once they're lined up, the app plays through them in turn, fading automatically between the end of one and the start of another. It's fun, and though unsophisticated, it's designed well and may be exactly what you may need to keep the music throbbing at a party.
Adidas has released its first Windows Phone app, miCoach, a personal trainer. This nicely designed fitness app coaches you through your workouts, and integrates with Nokia's HERE Maps for navigation and Nokia Music so you can listen to tracks as you jog along. It's free.
This article originally appeared in The New York Times.