Why were punchcards so popular and what is the reason they became obsolete?

Punchcards predate the existence of electronic computers themselves; the first commercially available computers produced by what is now IBM used punchcards. They were popular because, for nearly 100 years, there was no form of storage that was both cheap and reliable to replace it. However, by the mid-70s, other forms of storage were more readily available, so punch card usage pretty much died out. To understand why they were undesirable with suitable alternatives, think of the size of almost any program you would want to use today. Now think of how you would express that data on a punch card. Even if you used hex codes to represent each byte of a program (most punch cards were used mainly to perform arithmetic on numbers), it could take thousands of holes to express that program. This would require the usage of either very large punch cards which would be awkward to load, cards with very small holes that could no longer be punched by hand and with more moving parts, or the loading of hundreds or thousands of cards, which could take hours.