Bagels have their origin as a traditional food among the Jews of 16th century Poland.
Because fresh bread was a staple food but no cooking could be done on the Sabbath, the bagel dough would be prepared before the Sabbath and then placed in a cool place to slowly rise throughout the course of the day.

Once the Sabbath was over, the dough would be immersed briefly in boiling water and then baked. The reason for the boiling is murky, but the effects are clear: boiling gives the outside of the dough a thick, chewy crust that prevents the inside of the dough from rising much during baking. This, in turn, makes the inside of a bagel dense and also chewy.

Most bagels sold in supermarkets and even bagel shops across the United States lack this signature texture, because boiling each individual bagel is a labor-intensive process that would raise manufacturing costs significantly.

To avoid these costs, most modern manufacturers instead use machinery to steam the bagels before baking. Unfortunately, this does not produce the same texture as the traditional method, leaving many bagel purists with no choice but to make their own.