Antenna Tuners- What They Do.

This shows how a tuner allows one antenna to work on multiple HF radio bands. Sure there is some power lost in a tuner, BUT it is convenient and cheaper/easier than a million antennas.

Yes you can buy or make some antennas that are resonant on multiple HF bands, but often times if you look at the specs, they claim a 2.1:1 SWR. I've always used a tuner and have had contacts all over. To each their own though!