how do we known that the sun is the biggest star

Question: how do we known that the sun is the biggest star
- Keywords:
  sun
Asked by made43sun to Jason, Jenny, Janis, Daoud, Caitríona on 18 Nov 2019. This question was also asked by crenix.
- Janis Aleksans answered on 18 Nov 2019:
  
  The Sun is actually not the biggest star, it is quite average in fact. If you look in the sky, you can notice all stars have slightly different colour, the largest stars out there are blue in colour!

Question: how do we known that the sun is the biggest star