Some sources state that the term blues is related to "blue notes", the flatted, often microtonal notes used in blues, but the Oxford English Dictionary claims that the term blues came first and led to the naming of "blue notes".

Lyrical themes that frequently appeared in prewar blues, such as economic depression, farming, devils, gambling, magic, floods and drought, were less common in postwar blues.

The writer Ed Morales claimed that Yoruba mythology played a part in early blues, citing Robert Johnson's "Cross Road Blues" as a "thinly veiled reference to Eleggua, the orisha in charge of the crossroads".

It was only in the first decades of the 20th century that the most common current structure became standard: the so-called AAB pattern, consisting of a line sung over the four first bars, its repetition over the next four, and then a longer concluding line over the last bars. Handy wrote that he adopted this convention to avoid the monotony of lines repeated three times.

Two of the first published blues songs, "Dallas Blues" (1912) and "Saint Louis Blues" (1914), were 12-bar blues with the AAB lyric structure. The lines are often sung following a pattern closer to rhythmic talk than to a melody.

In the 1960s and 1970s, a hybrid form called blues rock developed, which blended blues styles with rock music.

As time went on, the phrase lost the reference to devils, and "it came to mean a state of agitation or depression." By the 1800s in the United States, the term blues was associated with drinking alcohol, a meaning which survives in the phrase blue law, which prohibits the sale of alcohol on Sunday.

Blues shuffles or walking bass reinforce the trance-like rhythm and form a repetitive effect known as the groove.

Blues as a genre is also characterized by its lyrics, bass lines, and instrumentation.

and musical form originated by African Americans in the Deep South of the United States around the end of the 19th century.

The genre developed from roots in African musical traditions, African-American work songs, spirituals, and the folk music of white Americans of European heritage.

Blues songs with sexually explicit lyrics were known as dirty blues.