What is "amateur radio" ?

• Videos (Youtube)
• Amateur radio (Wikipedia)
• Amateur radio operator (Wikipedia)
• Amateur radio call signs (Wikipedia)
• Radiosport (Wikipedia)
• Contesting (Wikipedia)
• What is Ham Radio? (Radio Society of Great Britain)
• What is Ham Radio? (American Radio Relay League)
• Introduction to Amateur Radio
• Amateur radio - a 21st Century hobby

What is "Summits On The Air" (SOTA) ?