幕后 mùhòu behind the scenes

怎么记住“幕后”: 幕 curtain + 后 back = behind the scenes.

汉字

Behind the scenes - 幕后黑手 (mùhòu hēishǒu) the hidden hand behind it all; 幕后花絮 behind-the-scenes footage.
From theater (behind the 幕, curtain); now standard for whoever/whatever operates out of public view - 幕后英雄 (unsung hero), 幕后交易 (backroom deal), 幕后老板.
Contrast 台前 (táiqián, front-of-stage/in public), its natural opposite. Often carries an intrigue or hidden-influence flavor.