Underdye Hair (Undercolor/Peekaboo): Best Colors, What to Ask For & Easy Maintenance

Curious about under dye hair (aka underdye/undercolor hair)? Here’s what it is, the most flattering shades (red, pink, purple, blue, blonde/white), how it looks on dark hair, how salons section/lighten it, and my simple routine to keep the color vibrant with minimal upkeep.