Not everyone needs an amazing bookmarking service they can use like a pro. For the casual reader, Facebook just introduced a feature called "Save". Now, if you see an article in your News Feed that you'd like to read later, just tap the Save button and Facebook will hang on to it.
Items you save will show up in their own special section, in the same area you find common groups, messages, or events now. This is little more than a fancy bookmarking tool. However, it's tied into your Facebook account and synced across devices, so you don't need to sign up for another service or install extra apps to use it.