Data scientists help people create knowledge from data, including sometimes million of gigabytes of data. An example is iTunes using the number of songs and length of each song on a CD to find the name of the CD, the artist, and the titles for each song. To data scientists, tracks on a CD are not music, but data.
Until the turn of the century, someone's knowledge was limited by their access to a library or university. Now, because of the increasing power and storage capacity of computers, and the increase in data being published, someone's knowledge is limited by their ability to process data. For example, for $600 you can buy a hard drive capable of storing all the music in the world.