A style of Basque music, Bertsolaritza is a form of acapella, improvised, poetic song which can describe a wide array of topics from societal problems to love. Bertsolari (the person performing) are given a topic and then must sing their piece within the metre – although there are many different paradigms to follow.
The most common (formal) metres are:
Each of these metres describes the amount of syllables required in a stanza or puntua in Basque. There are also many other informal styles for metre which constantly change via improvisors in casual settings.
The first bertsolari to perform was Fernando Amezketarra in 1799 at Azpeitia. Two years later he was involved in a Bertsolaritza competition; the prize being five ounces of gold. It gathered a crowd of 4,000 people and lead to the first tie in bertsolari history. This battle popularized bertsolari competitions to the prominence they have today.
Here’s a link to a video describing Bertsolaritza with a portion of a song: