当今 (dāng jīn) is a formal noun meaning 'the present time' or 'nowadays', often used attributively (e.g. 当今社会 'today's society'). It is more formal and literary than 现在 (xiàn zài) and 如今 (rú jīn), and unlike 现在, it cannot be used as an adverb meaning 'right now'. 当代 (dāng dài) refers to a broader 'contemporary era', while 当前 (dāng qián) can also mean 'currently' as an adverb.