As a humble beginner in the world of programming, and flicking through all the answers here after seeing this word used a lot in apparently slightly different ways in different places, I found reading the Wikipedia page on Bootstrapping (duh! I didn’t think of it either at first) is very informative to understand differences in use of this word. Could it be……on extremely rare occasions……Wikipedia might even have better explanations of certain terms than….(redacted)? Will they bring in rep points on Wikipedia though?
To me, it seems all the meanings something to do with: start with something as simple as possible Thing1, make something slightly more complex with that Thing2, and now you can use Thing2 to do some kind of tasks more efficiently and quickly than you could originally with Thing1. Then repeat from Thing2 to Thing 3 ad infinitum…
I see it as closely connected to both biological evolution and ‘Layers of Abstraction’ (newbies like me see, ahem, Wikipedia, cough) – the evolution from 1940’s computers with switches, machine code, Assembly, C, Python, AIs you can give all kinds of complex instructions to like “make the %4^% dinner to my default &^$% requirements and clean the floor you %$£”@:~” in drunken slang English or Amazon tribal dialect without them ‘raising an exception’ (for newbies again…you guessed it) – missed out lot of links there due to simple ignorance.
Then in certain specific software meanings: Meaning1: Thing1 is used to load latest version of Thing2 (because of course Thing2 will be bigger than Thing1, just as Thing3 will be be bigger than Thing2).
Meaning2: Thing1 is a lower level language (closer to 1001011100….011001 than print(“Hello, “, user.name)) used to write a little bit of the higher language of Thing2, then this little bit of Thing2 is used to expand Thing2 itself from baby vocabulary level towards adult vocabulary level (Thing2 starts to be processed, or to use correct technical term ‘compiled’, by the baby version of itself (it’s a clever baby!), whereas the baby version of Thing2 itself could of course only be compiled by Thing1, cause it can’t exist before it exists, right duh!), then child version of Thing2 compiles Surly Teenager version of Thing2, at which point programming community decides whether Surly Teenager’s ‘issues’ (software term and metaphor term!) are worth spending enough time resolving to be accepted long term, or to abandon them to (not sure where to take the analogy here).
If yes, then Thing2 has ‘Bootstrapped’ itself (possibly a few times) from babyhood to adulthood: “the child is the father of the man” (Wordsworth, suggest don’t try looking up the quote or the author on Stack Overflow).