Joyo (general-use) kanji, which currently number 1,945, are the characters officially approved by the Japanese government for use in newspapers and government publications. Japanese schoolchildren study these during their nine years of compulsory education, and non-Japanese speakers must do battle with them, too, to pass the top level of the Japanese Language Proficiency Test.
A number of commonly used kanji compound words (jukugo,) comprise kanji not listed as joyo, but this is set to be remedied with next year's revision — the first since 1981 — of the joyo list. As mentioned here last month, a 15-member Council for Cultural Affairs committee has vetted candidates for joyo inclusion since 2005 and is poised in March to recommend the addition of about 200 kanji, which it unveiled in September. As well as frequency of use, jukugo-building muscle gave many kanji the competitive edge needed to survive thus far.
Expected joyo inductee 葛 (KATSU, kudzu) is one half of the commonly used jukugo 葛藤 (kattō, kudzu/wisteria, "discord"). Its compound word-building power enabled 葛 to edge out fellow botanical contenders 栗 (kuri, chestnut) and 蘭 (RAN, orchid). 藤 (TOU, wisteria), also a joyo newbie, features in three of Japan's most common surnames (No. 1: 佐藤, Satō; No. 6: 伊藤, Itō; and No. 10: 斎藤, Saitō).