Lo-fi is a music or production quality in which elements usually regarded as imperfections in the context of a recording or performance are present, sometimes as a deliberate choice. The standards of sound quality (fidelity) and music production have evolved over the decades, meaning that some older examples of lo-fi may not have been originally recognized as such. Lo-fi began to be recognized as a style of popular music in the 1990s, when it became alternately referred to as DIY music. Some subsets of lo-fi music have become popular for their perceived nostalgic and/or relaxing qualities, which originate from the imperfections that define the genre.

Fidelity is the quality of faithfulness or loyalty. Its original meaning regarded duty in a broader sense than the related concept of fealty. Both derive from the Latin word fidēlis, meaning "faithful or loyal". In the City of London financial markets it has traditionally been used in the sense encompassed in the motto "my word is my bond".