What is bootstrapping?

I keep seeing "bootstrapping" mentioned in discussions of application development. It seems both widespread and important, but I've yet to come across even a poor explanation of what bootstrapping actually is; rather, it seems as though everyone is just supposed to know what it means. I don't, though. Near as I can figure, it has something to do with initialization tasks required of an application upon launch, but I could be completely wrong about that. Can anyone help me to understand this idea?

"Bootstrapping" comes from the term "pulling yourself up by your own bootstraps." That much you can get from Wikipedia.

In computing, a bootstrap loader is the first piece of code that runs when a machine starts, and is responsible for loading the rest of the operating system. In modern computers it's stored in ROM, but I recall the bootstrap process on the PDP-11, where you would poke bits via the front-panel switches to load a particular disk segment into memory, and then run it. Needless to say, the bootstrap loader is normally pretty small.

"Bootstrapping" is also used as a term for building a system using itself -- or more correctly, a predecessor version. For example, ANTLR version 3 is written using a parser developed in ANTLR version 2.

An example of bootstrapping is in some web frameworks. You call index.php (the bootstrapper), and then it loads the frameworks helpers, models, configuration, and then loads the controller and passes off control to it.

As you can see, it's a simple file that starts a large process.

The term "bootstrapping" usually applies to a situation where a system depends on itself to start, sort of a chicken and egg problem.

For instance:

• How do you compile a C compiler written in C?
• How do you start an OS initialization process if you don't have the OS running yet?
• How do you start a distributed (peer-to-peer) system where the clients depend on their currently known peers to find out about new peers in the system?

In that case, bootstrapping refers to a way of breaking the circular dependency, usually with the help of an external entity, e.g.

• You can use another C compiler to compile (bootstrap) your own compiler, and then you can use it to recompile itself
• You use a separate piece of code that sets up the initial process without depending on any functions provided by the OS
• You use a hard-coded list of initial peers or a hard-coded tracker URL that supplies the peer list

etc.

See on the Wikipedia article on bootstrapping.

There is a section and links explaining what it means in Computing. It has four different uses in the field.

Here are some quotes, but for a more in depth explanation, and alternative meanings, consult the links above.

> "...is a technique by which a simple computer program activates a more complicated system of programs." > >"A different use of the term bootstrapping is to use a compiler to compile itself, by first writing a small part of a compiler of a new programming language in an existing language to compile more programs of the new compiler written in the new language."

In the context of application development, "bootstrapping" usually comes up when talking about modular and/or auto-updatable software.

Rather than the user downloading the entire app, including features he does not need, and re-downloading and manually updating it whenever there is an update, the user only downloads and starts a small "bootstrap" executable, which in turn downloads and installs those parts of the application that the user needs. Additionally, the bootstrap component is able to look for updates and install them each time it is started.

Alex, it's pretty much what your computer does when it boots up. ('Booting' a computer actually comes from the word bootstrapping)

Initially, the small program in your BIOS runs. That contains enough machine code to load and run a larger, more complex program.

That second program is probably something like NTLDR (in Windows) or LILO (in Linux), which then executes and is able to load, then run, the rest of the operating system.

For completeness, it is also a rather important (and relatively new) method in statistics that uses resampling / simulation to infer population properties from a sample. It has its own lengthy Wikipedia article on bootstrapping (statistics).

Boot strapping the dictionary meaning is to start up with minimum resources. In the Context of an OS the OS should be able to swiftly load once the Power On Self Test (POST) determines that its safe to wake up the CPU. The boot strap code will be run from the BIOS. BIOS is a small sized ROM. Generally it is a jump instruction to the set of instructions which will load the Operating system to the RAM. The destination of the Jump is the Boot sector in the Hard Disk. Once the bios program checks it is a valid Boot sector which contains the starting address of the stored OS, ie whether it is a valid MBR (Master Boot Record) or not. If its a valid MBR the OS will be copied to the memory (RAM)from there on the OS takes care of Memory and Process management.

As the question is answered. For web develoment. I came so far and found a good explanation about bootsrapping in Laravel doc. Here is the link

> In general, we mean registering things, including registering service > container bindings, event listeners, middleware, and even routes.

hope it will help someone who learning web application development.

Bootstrapping has yet another meaning in the context of reinforcement learning that may be useful to know for developers, in addition to its use in software development (most answers here, e.g. by kdgregory) and its use in statistics as discussed by Dirk Eddelbuettel.

From Sutton and Barto:

> Widrow, Gupta, and Maitra (1973) modified the Least-Mean-Square (LMS) > algorithm of Widrow and Hoff (1960) to produce a reinforcement > learning rule that could learn from success and failure signals > instead of from training examples. They called this form of learning > “selective bootstrap adaptation” and described it as “learning with a > critic” instead of “learning with a teacher.” They analyzed this rule > and showed how it could learn to play blackjack. This was an isolated > foray into reinforcement learning by Widrow, whose contributions to > supervised learning were much more influential.

The book describes various reinforcement algorithms where the target value is based on a previous approximation as bootstrap methods:

> Finally, we note > one last special property of DP [Dynamic Programming] methods. All of them update estimates > of the values of states based on estimates of the values of successor > states. That is, they update estimates on the basis of other > estimates. We call this general idea bootstrapping. Many reinforcement > learning methods perform bootstrapping, even those that do not > require, as DP requires, a complete and accurate model of the > environment.

Note that this differs from bootstrap aggregating and intelligence explosion that is mentioned on the wikipedia page on bootstrapping.

In terms of it in regards to using the popular Twitter Bootstrap I feel like this type of bootstrapping is the action of integrating a modular component into a Web application without the Web application having to even acknowledge the modular component exists until it needs it or references it.

The developer can seamlessly integrate a default copy of the CSS Twitter Bootstrap theme by simply loading (referencing) it into the Web application. Vuola! Then you may need to override some of these changes, but you can do so in such a way that the resource/component is untouched and completely reusable.

This same concept is how Web Devs implement jQuery APIs and so on, but it's not really expressed by Devs as bootstrapping per se. What it does is it improves flexibility and reusability while allowing the isolation of different components/resources of an app to reside freely either on the same server/s or possibly on a CDN.

NOTE: In computing bootstrapping deals with the MBR and in UNIX it requires a special bootloader or manager which is a small program in ROM that loads the OS into RAM. If you think about it the same concept takes places in the action of the bootstrap loader checking the MBR and loading the OS based on this table which occurs without the OS having any idea that this takes place.

IMHO there is not a better explanation than the fact about https://stackoverflow.com/questions/1653649/how-was-the-first-compiler-written

These days the Operating System loading is the most common process referred as Bootstrapping

I belong to the generation who flipped switches to enter a boot program. In the early 1980s, I worked on a microcomputer called Micro-78, developed by Electronics Corporation of India Ltd (ECIL). It was a sort of clone of Altair 8800. I distinctly remember what happens when a small boot program was entered using the toggle switches and executed by pressing a button. The program reads a second boot program contained in the 1st track of the floppy disk and overwrites it on itself in such a way that the second boot program starts executing to load a disk operating system. I think the term "bootstrap" refers to this process of the first boot program reading and overwriting the second boot program on itself, in a way "pulling itself up" with the additional functionality of the second boot program. That may be the origin of the original meaning of "the bootstrap program".

Bootstrap file is responsible for loading contents of main file. It is a wrapper around main file. This way we can catch errors if loading of file was unsuccessful for some reason.

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).