Used in affirmative or general statements to mean 'all things' or 'any matter'. Often appears in proverbs or advice.
Everything is an experience.
Everything is difficult at first.
Used with a negative verb to mean 'nothing' or 'not anything'. The negative form is essential.
Nothing happened.
彼は何事もなかったかのように振る舞った。
He acted as if nothing had happened.
Standard kanji spelling.
Mixed kana spelling, sometimes used for clarity or emphasis.
Compound of 何事 (nanigoto, 'what thing/matter') + particle も (mo, 'also/even'). The combination yields 'whatever thing' → 'everything/anything', and with negation 'nothing'.