Hey there!
Terrorist groups are becoming more common because they're widespread.
In other words, they're so many of them hidden in plain sight that it's hard to stop them. Anybody, anywhere, could be one, and the government might not know until it becomes too late.
This has definitely affected arious countries. We'll go with Syria. Groups there have destroyed a lot of the country, and since they're so hard to stop, it will be quite difficult to rid the country of them.
Just like in Syria, other countries like Yemen and Lebanon have been affected, and have been hit very hard. If we can't find out a way to stop this, we could be in serious danger.
Hope this helps