If I understand it correctly, when using the -vce(bootstrap)- command for a regression, Stata will randomly draw _N observations from the sample 50 times (by default) to calculate the t statistic.

Stata provides users the ability to control the size of bootstrapped samples with the -size(#)- parameter. However, I'm a bit confused as to what Stata does if -size(#)- is not defined. The help section says by default _N is the number of observations in the sample... so is Stata drawing _N observations for every bootstrapped sample?

For example, if I have a sample of 10,000 observations, when bootstrapping does Stata draw 10,000 observations of each bootstrap repetition? How does that make sense?