Explain like I only speak in plain English

In programming, a library is a collection of programs that perform specific tasks. Engineers incorporate libraries into their projects so they don't have to write the programs themselves, to save development time.

Different libraries solve different problems, big or small. Engineers pick and choose the libraries they use based on their project needs. Using a library is like installing a pre-built engine into a car, versus building an engine from scratch.

An engineer that uses libraries is like a car manufacturer that sources ready-made parts from other manufacturers. The engineer just needs to assemble all the parts together and make sure it runs, with some fine-tuning.

Explain like I'm a total nerd

To avoid reinventing the wheel, programmers create and share standalone programs for a specific use case as a library for others to easily incorporate into their projects.

Most programming languages support the use of libraries, and often have a library management system that deals with installing, versioning, and updating the libraries used in a project.

JavaScript projects mainly use NPM for managing libraries. Ruby projects use RubyGems to manage libraries.

Explain like I'm an artist

Using libraries for development is like opening an art gallery. You don't necessarily need to know how to create art. Your work is to choose the right artwork and create a consistent atmosphere that tells a story.

Explain like I already know it

The use of libraries can save a lot of development time. However, engineers should strive to understand how a library works before they use it. The level of understanding should be deep enough that they could build it themselves if it becomes necessary.

Also, not all libraries are created equal. It is important to choose libraries that are soundly designed and well built, maintained and kept up to date. You can usually check this by the number of stars and issues, frequency of releases of the library repository on GitHub.

jQuery

jQuery is a JavaScript library that helps front-end web engineers add interactive features to a website. In essence, it is a collection of commonly used stand alone tools that front-end engineers use to build websites.

NPM

NPM, short for Node Package Manager, is a package manager for JavaScript libraries. NPM is used to deal with installation, removal, updates of JavaScript packages in both front-end and back-end projects.

Bootstrap

Bootstrap is a CSS framework that lets front-end web engineers add style structure to websites very quickly. Bootstrap provides a set of standards in spacing, typography, color, interactive behaviors, and more.

RubyGems

RubyGems is a package manager for Ruby libraries. RubyGems is used to deal with installation, removal, updates of Ruby libraries. RubyGems libraries are called Gems for short.

Framework

In programming, a framework is a standard for building applications. Frameworks deal with low level details so engineers can focus on high level problems that actually matter. Frameworks can significantly reduce development time.