Heavy metal is a science in and of itself. Even though the genre isn't even 50 years old yet, so many subgenres have developed that it's easy to get overwhelmed. What exactly is the difference between traditional doom metal and avant-garde metal? And how is thrash metal related to death metal?

Google "metal" and "map" and you'll quickly find a crash course on the web with a number of charts and tables. In great detail, they trace the historical and geographical development, from the blues in the 1960s to the dozens of subgenres that define the metal scene today.

But those are just words and drawings. You can't really understand the music until you experience it live in the company of true metalheads at Wacken Open Air. There at the Bullhead City Circus Tent, you can find out how metal bands from all over the world interpret the genre in 2016.

Wacken's Metal Battle

This week on August 3 and 4, artists from 28 countries will be battling it out in Wacken. They've come to one of the world's most famous metal festivals from China, Argentina, Romania, Trinidad and Tobago, and a host of other countries to show what they've got - and they only have 20 minutes of stage time to do so.

The participating bands have to convince both the live audience in the Circus Tent and a jury of experts. Last year's winners - Vesperia - came from Toronto, Canada, and play classic death metal. Drummer Dylan Gowan pushes the group's sound with quick rhythms, Frankie Caracci throws in aggressive melodies on the guitar, and lead singer Morgan Rider gives the band its distinctive sound with his throaty vocals.

Headbanging broke out throughout the tent as Vesperia presented their wild, loud and sweaty performance in 2015 - and took home first prize.

While they may seem gruff and even scary on stage, the musicians were polite and talkative interview partners after the show - which is also typical for Wacken. After the awards ceremony, the Canadians even seemed a bit embarrassed that they left the international competition in the dust. Vesperia knows how high the skill level is in the Metal Battle contest.

"It doesn't matter what language you speak or where you're from, everyone can understand our music," said frontman Morgan Rider. "We're all metal fans."

Music, not politics

There's no doubt that this music builds bridges and brings people together. That was particularly apparent during the 2015 Metal Battle. The second- and third-place winners came from conflict regions: Israel and Lebanon. The Middle East may be a volatile place, but in Wacken the musicians quickly forget their differences.

"We're a small country. Around 200 people come to concerts in clubs. And 800 to 1,000 people come to festivals," said Bassem Deaibess, the Lebanese frontman of the band Blaakyum.

In Israel, heavy metal is a small subculture, explained bassist Avihai Levy from Walkways. "In Israel, there are tons of talented musicians. But to get to Wacken, we had to go up against many of our friends who we think are very good."

This year marks the 13th Wacken Metal Battle. Organizers say the contest isn't just a time-filler between shows by headliners like Iron Maiden, Steel Panther and Bullet for My Valentine. On the contrary, festival director Thomas Jensen and his team invest a lot of money, manpower and stage time every year to get the young international bands to Germany and offer them a professional set-up.

The top five Metal Battle winners receive four-figure cash prizes, paid for by the Wacken Foundation, as well as stage equipment from sponsors - and a TV report on DW's music show PopXport.

Making international connections

Each year, the Wacken Metal Battle organizers try to make connections to new countries in order to keep the contest musically and culturally as exciting and diverse as possible. Belgians and Scandinavians are always represented, and China and Brazil are also regulars. This year, fans can look forward to bands from South Africa, India and the Caribbean. There is even a Greek band on the schedule that pimps its sound with a bagpipe.

It might sound as corny as many an electric guitar, but it's true: You'll find everything at Wacken. There are only winners at the Metal Battle. The fans get to experience 28 performances by artists they wouldn't otherwise have a chance to see. The organizers expand their international network. And the participating musicians get a trip to northern Germany - which is comparable to a pilgrimage to the holiest of metal destinations.