npm install automatically add ^(caret) in package-lock

Previously relevant part in package-lock was looking this way

"requires": {
    "@babel/highlight": "7.0.0"
  }

But now it includes the caret(^) after running npm install.

"requires": {
    "@babel/highlight": "^7.0.0"
  }

(note - this contains only a small potion of package-lock)

Can anyone explain the reason for this?