Sertanejo started in central Brazil, far from the coast - in the wide, dry farmland where people grew up working the land. The first sertanejo songs were sung by people on horseback or in farmhouses, accompanied by an acoustic guitar called the viola caipira (which has 10 strings instead of 6).
Most sertanejo singers are duos - two voices singing together in tight harmony. Often the two singers are brothers or sisters, or best friends who've been singing together since childhood. The matching voices are one of the things that make sertanejo feel cosy and familiar.
Sertanejo is the most popular kind of music in Brazil today. Sertanejo concerts can fill stadiums with tens of thousands of fans, all singing along to every word. Many of the biggest sertanejo stars started out playing in tiny country bars before becoming famous.
If you want to spot a sertanejo song, listen for: two voices singing in harmony, an acoustic guitar, sometimes an accordion, and stories about love, friendship, the countryside, or the city missing the countryside. Songs you can sing along to are a big part of the style.