I was reading something today which mentioned phonetic radicals.  What’s that?

“The right side is usually what’s known as the “phonetic compound.” This portion has a specific reading attached to it. If you see this phonetic compound, you can sometimes guess the reading of the kanji. Sometimes by learning one phonetic compound’s reading you can know how to read six or seven other kanji that contain it.”

Apparently 67% of kanji have phonetic radicals, so it would be very useful to learn them.