waves

1. electromagnetic waves

1.1. radio waves

1.2. microwaves

1.3. infrared waves

1.4. visible light

1.5. ultraviolet radiation

1.6. X-rays

1.7. gamma rays

2. mechanical waves

2.1. longitudinal wave

2.1.1. rarefaction

2.1.2. compression

2.1.3. sound

2.2. Surface wave

3. transverse

3.1. crest

3.2. trough