Inflation

I'll often hear people comment on how expensive food is becoming, but when reflecting I'm sure that I've heard this each year for most of my life... so I wonder if it's not just like the passing of time - each year we comment on how fast the year has flown past, but in reality nothing's changed - the year hasn't progressed faster.

While inflation takes it's toll on peoples budgets it seems to be something that will never be escaped and something that we'll always survive. Now with this in mind, can someone please explain to me exactly why we have inflation. It seems like year on year prices increase, and salaries increase to follow suit - so why not keep prices constant and salaries the same? There must be a reason that I'm failing to understand - please will someone educate me?