symbl-data/loc/en/blocks/kangxi-radicals.axyml

Kangxi radicals, named for the eponymous emperor, are a list of 214 Chinese characters, used originally in the 1615 Zihui and adopted by the 1716 Kangxi Dictionary. This works lists radicals in stroke count order, along with examples of characters using them, and has become such a common standard that sometimes radicals are referred to by number alone. A reference to "radical 61", for example, without additional context, means 心; xīn.