I heard that an antenna picks up signals of all frequencies, and then these signals are filtered by a circuit using an inductor and capacitor, and that this is how a radio is tuned.

However, I also heard that an antenna has a resonant frequency, and that this is determined by its length.

• Does this mean that it will only pick up signals at or near to its resonant frequency?
• What then is the point of a tuning circuit?
• And what about transmitting antennas? Will they naturally transmit signals at their resonant frequency without the need of a tuner?