This is a difficult question to answer, but we can provide a very rough estimate. In our galaxy alone, there are roughly 10¹¹ to 10¹² stars. Then consider that there are roughly 10¹¹ to 10¹² galaxies in total, and, if we assume the other galaxies are similar to ours, this would put the total number of stars in existence somewhere between 10²² to 10²⁴ stars. Clearly there are too many to count!