system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How was the first software created and integrated into computers when there wasn't any software to do it?
gpt
Physical punchcards (card with holes dotted on them) were fed into computers to set memory switches on or off which would then act as the program and data to be executed.

When a basic computer is "booted" its instruction pointer points to a location in memory.  The 1's and 0's at that location are retrieved and depending on what's there different actions are caused: that might be loading a memory location, adding two numbers together, or storing the result.   Using a relatively small set of instructions, vastly complicated processes can be made.

Computer data, being binary, has always been interpretable as numbers.   Eventually punchcards were phased out in favour of analogue tape which stored the numbers as magnetic patterns on the strip.   Analogue tape gave way to magnetic disks (floppy disks) and magnetic harddrives then solid state drives (SSDs) which is basically 'now'.

Fundamentally the same thing is being done as with the punchcards, just the process is faster.