AAVSO observer, Bob King, wrote a piece in his blog called The Biggest Star in the Sky and How to Observe It.
It's a great introducton to VY Canis Majoris, a hypergiant star approximately 2000 times the size of our Sun.
It's a nice non-technical article with several great images. Check it out!
In an excellent article Steve Gottlieb talks about this VY CMA star in Sky And telescope, march issue (pages 66-67).