Ideographic characters are one of the Six Categories of Chinese character formation.
Tips
culture
The 六书 (liùshū 'Six Categories') is the traditional classification of Chinese characters from the Han-era 《说文解字》. The six are: 象形 pictographs, 指事 ideographs, 会意 compound ideographs, 形声 phono-semantic compounds, 转注 derivative cognates, and 假借 phonetic loans.
memory
指 = 'to point at' + 事 = 'a thing/concept' + 字 = 'character'. A 指事字 'points at' an abstract idea — e.g. 上 is a mark above a baseline (= 'up'), 本 is a mark at the base of 木 (= 'root').