waves

1. mechanical waves

1.1. longitudinal wave

1.1.1. rarefaction

1.1.2. compression

1.1.3. sound

1.2. Surface wave

2. transverse

2.1. crest

2.2. trough

3. electromagnetic waves

3.1. radio waves

3.2. microwaves

3.3. infrared waves

3.4. visible light

3.5. ultraviolet radiation

3.6. X-rays

3.7. gamma rays