A lot of people seem to suggest to do a podcast, it is fine to just plug a USB mic into your computer and press record.

This may not be the solution for everyone. 

If you have your PC on you may also record the sound of your computer fan or hardrive or indeed other electrical noises. 

It may be better to record on an external microphone into an external recorder. 

This means you can record in a different room or outside or on location without being connected to your computer. 

However if you are doing such as a live YouTube talk, then a USB microphone may make life simpler.