How can a sourdough starter be 100 years old?

Question

I keep seeing sourdough starters all over socials. How can sourdough starters be many years old. Don’t you need to use the starter to make the bread? ELI5!

In: Other

Answer 1

Sourdough starter contains yeast and bacteria. These grow and multiply as long as you ‘feed’ the starter with flour and water.

So a 100 year old sourdough starter has been given more water and flour for 100 years. This keeps making it bigger, so some can be used for baking bread and you still have plenty leftover.