By now, you’ve noticed the hordes of people slowly shuffling through the streets, crowding around landmarks and churches and bus stops, their fingers mysteriously flicking their phones. Every now and again, there is a cry of “Charizard,” and the entire herd moves more quickly than you could have imagined, stampeding down the street and out of view.

No, there’s been no surprisingly placid zombie apocalypse. It’s just Pokémon Go!

Pokémon, pronounced “POH-kay-MON,” is an incredibly popular game and media franchise created by Satoshi Tajiriin 1995. Tajiri drew inspiration from his childhood hobby, insect collecting, to develop a game in which players captured, trained, and traded a wide variety of fantastical creatures whose myriad designs were inspired by insects, old Japanese shows, and anime.

Playing the many Pokémon games involves two simple concepts—catch em’ all and win. Within the fictional Pokémon world, Pokémon are captured by players, who then teach them fighting moves and train them for battle. The more battles a Pokémon wins, the stronger it becomes, eventually undergoing a metamorphosis and evolving into a more powerful form. Players create teams of their best Pokémon, using them to battle other fictional Trainers within the game, as well as other real players through multiplayer play.

A Pokémon is caught by weakening it through a Pokémon battle, and then throwing a Poké Ball at it, which captures it, adding the creature to the player’s collection and creating an entry in their Pokédex —a device which records and displays detailed information about each Pokémon as it is captured.

Players venture through the Pokémon world, defeating well-established computer-controlled Trainers called Gym Leaders, who are especially powerful. When a player defeats a Gym Leader, they are given a Gym Badge. Any Trainer who earns eight Gym Badges is eligible to face the Elite Four—the most powerful Trainers—and go on to win the Pokémon League Championships.

To compare Pokémon to sports, the player is the coach of a relatively unknown football team that has to learn the rules, train, and overcome nearly impossible odds to defeat all the big teams and win the Super Bowl. Pokémon, with its roots in the 1990s, is an extremely fond memory for many people, even those who haven’t kept up with the game’s many sequels throughout the years. The word Pokémon brings to mind the feelings of camaraderie that came from trading and battling with friends, and excitedly talking about the latest catch or unexpected evolution—it’s the same feeling someone might get from seeing their favorite childhood band playing once again after a long hiatus.

And that’s a large part of why Pokémon Go has been such an overwhelming success. Not only do we now have access to Pokémon on our phones, but we get to live that childhood dream of actually going out into the world to look for Pokémon. It’s like not only seeing that favorite band again, but having the opportunity to meet its members.

Pokémon Go is a mobile game in every sense of the word. When players open the game, a map of their local area appears, fed by real GPS data which tracks their position. Upon this map are places called PokeStops—usually landmarks, restaurants, churches, and other notable places—that players can visit to gather Poké Ball and other consumable in-game items.

These stops are where many players congregate. In-game devices called Lures can be attached to a PokeStop, which draw in more Pokémon to be captured, which, in turn, draws more players. This is why certain places which feature several PokeStops clustered together—such as a museum or mall—are drawing such crowds of players.

In Pokémon Go, Pokémon appear on the players’ maps, and must be tapped with a finger in order to be engaged in battle. Unlike previous generations of Pokémon games, the player does not use their own Pokémon to weaken a wild Pokémon. To capture the creature, a player simply flicks a Poké Ball with their finger, throwing the ball at the Pokémon. If the ball strikes just right, the creature is caught. There are several strategies involved in this—it’s not a simple throw. You can learn tips in gameplay guides if you wish to play.

Although may Pokémon Go players are adults, there is also a sizable portion of children wandering around outside looking for Pokémon, and so many parents may be concerned, not wholly understanding what their children are actually participating in.

With the basic information out of the way, let’s take a look at a few of those concerns, and what you might want to talk to your kids about before they put on their Trainer hat and backpack and leave for the Pokémon Championships.