Grim memory Google

What does it mean when it has "1080p" vs "720p" and why does Hz matter? - akai tvs better than excellent

I think the purchase of a new plasma TV my 5 years after his break (it was an Akai, I hope the TV is today, built without dying earlier ...). The only difference I see between the different LCD or plasma TVs are quite in contrast to "Hz" and the difference in the "p".
Which brand is the "best" means that "p" and "Hz" really means, and can you recommend a decent 42 "TV from Best Buy, which is a lower tendency to crack? Thanks:)