This is What's Trending Today.

Pokemon Go can be called a phenomenon. The smartphone video game became popular almost overnight.

Millions of people have downloaded the game. Players are walking around cities in the U.S., Australia, New Zealand, Germany and a few other countries, trying to catch the Pokemon characters.

For the most part, it's all in good fun. People are getting outside more, walking around and even meeting their neighbors.

But some people think Pokemon Go players should try to use better judgment.

There were reports earlier this week of people hunting Pokemon at the U.S. Holocaust Memorial Museum in Washington, D.C. The museum is a memorial to Jews who were killed by Nazis in Europe in the 1930s and 1940s.

The museum has asked the game's makers to remove it from the sites where players can hunt the characters.

People have also reportedly been looking for Pokemon characters at the Arlington National Cemetery near Washington. The cemetery is where many U.S. military veterans are buried.

The cemetery posted this message on Twitter: "We do not consider playing Pokemon Go to be appropriate decorum on the grounds of ANC."

Will the negative reactions hurt the game's popularity?

Pokemon Go launched on July 6. Observers are trying to guess whether or not the game will remain hugely popular for a long time.

Some people are joking about the recent backlash. "Backlash" is a strong public reaction against something, usually something that has become very popular.

One person wrote on Twitter: "Dear internet, Please hold off on your Pokemon Go backlash..."

At least one company hopes the game stays popular. The stock of game-maker Nintendo increased over 50 percent last week after the game's release.

In the United States, businesses are already trying to find ways to take advantage of the game's popularity.

One pizza restaurant in New York says business increased by 75 percent over the weekend after it paid money to have Pokemon characters placed inside the restaurant. Customers came in, ate pizza, drank beer and played the game.

And that's What's Trending Today.

I'm Dan Friedell.

Dan Friedell wrote this story for Learning English. Ashley Thompson was the editor.