The free apps are iMovie, Pages, Numbers, Keynote, and GarageBand, and each can be downloaded now from the Mac and iOS App Stores. Anyone who wants to check out iWork, iMovie and GarageBand can now do so without having to pay for them.
For reference, the entire iWork suite used to cost $30 on iOS and $60 on Mac, while iLife used to run for $10 on iOS and $20 on Mac.
These apps were previously only free for customers who purchased a new Mac or iOS device, but Apple has now removed this condition and made the apps free for all customers, no matter the device. This eliminates the need to buy new Apple hardware to get these apps for free. For all users who bought Apple hardware post 2013, you're likely going to see no change as such, but old hardware users will now see these apps as free on respective stores.
Bringing a little something for everyone, Pages, Numbers, and Keynote tools are Apple's answer to Microsoft's globally dominant Word, Excel, and Powerpoint programs. Freeing these app wasn't a new decision though and the company was already offering free versions through new purchases of Mac or iPhones. Apple has included each of the iWork apps for free with every iOS device that was activated at or after September 2013 and free for Mac hardware activated on or after October 2013.
iMovie is a basic video editing app, while GarageBand focuses on music editing.
According to MacRumors, the apps have been made free so that businesses and educational institutions can easily access them. However, expect the page to update its contents once the price drop starts rolling or takes effect.
You can find out more details about the above apps over at the iTunes app strore, they are now free for the iPhone, iPad, iPod Touch and also Apple's range of Macs.