Flashbulbs remained the most economical choice for occasional and amateur photographers well into the 1970's, when they sort of mutated into flash cubes and bars.
As you might expect, competition in the flashbulbs business created many different types and numbers, many of which are compatible with each other even though they have different names. Same bulb, different company, different number. Here at MFBOXCO, we are focused strictly on bulbs that work with cameras you can use today, and we will let you know which bulbs work with which flash attachments.
When you run current across a flashbulb, it explodes inside. Literally. They consist of just-thick-enough glass, and maybe an additional coating, to contain a very long filament that combusts in a flash of light in a fraction of a second. It's old-school super-heated fire going on in there.
Flashbulbs can be dangerous. Period.
Let that sink in for a second before continuing to read a few tips we've gathered to keep you and your subject out of the blast radius, so to speak.
In summary - be careful! The best practice is to buy at least a few boxes of bulbs in their original packaging and keep the sleeves to store bulbs you buy loose.
Thanks in advance to the guys at Graflex.org for not beating me up too badly for cribbing their safety precautions.