In an effort to make the iPhone more autonomous from your home computer, the iOS 6 allows you to do more with different download services.
You can update the firmware version, sync to your computer, and download all iTunes content remotely, which makes plugging it in seem almost archaic. This has also improved iTunes in an effort to make the purchase of songs an even more accessible item, which they hope will curb piracy and increase sales. One option is to actually preview the song that you are considering purchasing, which is great as more versions and remixes confuse the catalogue at iTunes. Here is a look at how to preview songs in iTunes from your iPhone.
Once you have identified your song, either from browsing or a direct search, look at its listing. You will see the name, the length, and then the price to the right. Go ahead and select the name of the song itself. An icon will replace the track number that shows a black square surrounded by a circle, that will be filled up clockwise as the song progresses. If you press that button again, which acts essentially as a “Stop” button, the track will cease playing. You can, theoretically, listen through all the songs on a given album to get a sense if you would like to purchase it or not.
You can also continue to listen to a song while you keep browsing. The song will play as you go through the store unless you actively turn it off by selecting the stop button, or if it is interrupted by something like the phone ringing or another song being selected. The same option is not quite as true for video content, though trailers are available.