This can be deliberate for example:

It is common to see this in some countries where they want to prevent foreign radio stations being listened to in their county, they will disrupt the information flow.

In a ‘war zone’ where radio jamming is an essential part of the protection of ground troupes and vehicles from radio/mobile phone triggered IEDs (Improvised Explosive Devices).

Or unintentional for example:

When an operator transmits on a frequency that is very busy

When equipment that radiates a signal accidently emits on say, an aircraft emergency frequency.

Deliberate jamming can be used to override any signal at the receiving equipment with enough power, Bluetooth and Wi-Fi do not need much to be overpowered.

The most common types are split into two main categories: obvious and subtle.

For example China plays a loop of traditional Chinese music whilst it jams stations from broadcasting. This is a very obvious type of jamming.