There are a few types of bloatware. There's the apps that come pre-installed that could slow it down, malicious software from websites or apps, or apps that you get from a play store, such as a game, that reduces your phone's ability to compute as efficiently.
Bloatware is basically a software that is preinstalled on the device by mobile carriers. In other words, you don't have a say in whether it is installed on your device or not.
