In 1999, there was a big conflict happening in a country called Yugoslavia. Yugoslavia was made up of different groups of people who didn't get along very well, and they were fighting with each other. One of these groups was called Kosovo, and they wanted to be independent and have their own country.
Another group in Yugoslavia was called Serbia, and they wanted Kosovo to stay part of their country. They fought with each other, and it became really violent and dangerous for the people living there. They were hurting each other, and many innocent people were getting hurt too.
To try to stop the fighting and protect the people, a group called NATO got involved. NATO is like a team of countries that work together to keep peace and protect people. They thought it was important to stop the violence in Yugoslavia, so they started doing something called bombing.
Bombing means that they sent airplanes to drop big, powerful bombs on specific places where they thought the bad guys were. They hoped that by doing this, they could make the bad guys stop hurting innocent people and make them listen to what NATO wanted.
One of the cities in Yugoslavia that got bombed was called Novi Sad. NATO thought that this city had important buildings that were helping the bad guys. They wanted to destroy those buildings so that the bad guys couldn't use them anymore.
But when you bomb a city, it doesn't just affect the bad guys. It also affects the innocent people who live there. Buildings get destroyed, and people can get hurt or even killed. That's why bombing is a serious decision, and sometimes people argue about whether it's the right thing to do.
In the case of the NATO bombing of Novi Sad in 1999, some people thought it was necessary to stop the fighting and protect the innocent people. But other people thought it was wrong because it hurt the innocent people too.
In the end, the bombing did have an effect, and the fighting in Yugoslavia eventually stopped. But it's still a sad event because many people lost their homes and loved ones, and it took a long time for things to get better in that part of the world.