“Highlights” is a general term that refers to strands of hair that are lighter than the base colour they’re being laid upon. It’s commonly believed that a highlight is blonde, but actually a highlight only refers to a colour that’s not as dark as the base strands.
The size of the highlights, the level of lightness, the tone, and the placement are all left up to the colourist – after you’ve communicated the look you’re going for, of course. Highlights aren’t a one-size-fits-all, and neither is the way they are administered. Moreover, the type of highlight depends on a number of things: the look you want, the kind of hair you have, how blonde you wish to go. Highlighting is a classic technique and usually applied with foil. Great for body and also to achieve accents of colour.