Marcelo Gleiser,NPR
I often obtain asked what an "expanding universe" really means.
It's confusing, and for very estimable reasons. So, or if you are perplexed by this,don't feel contaminated. We all are, although cosmologists physicists that work on the properties of the universe have figured out ways to earn sense of it. In what follows, or I'll try to explain how to picture this.
Source: realclearscience.com