What is a Programming Library? A Beginner’s Guide

Author headshot of Rachel Meltzer.

One of the most confusing parts of programming is navigating the jargon of the tech world. The two most confused words in development are programming library and framework.

Today, we’re going to talk about libraries. If you’re interested in the other half, check out our guide to frameworks.

Programming libraries are useful tools that can make a web developer’s job more efficient. They provide pre-written, reusable chunks of code that developers can use to create applications quickly and easily. 

Imagine you’re creating an application that allows people to purchase and participate in a course. You might turn to a free, open-source library to create user authentication for logging in. Or you could use a library to connect your app to a server. 

In this article, we’ll define the difference between a library and a framework, how developers use libraries, and go over the most popular programming languages. 

Want to jump ahead to a particular section? Just use the clickable menu: 

  1. What is programming?
  2. What is a programming library?
  3. How do developers use libraries?
  4. What’s the difference between a library and a framework?
  5. Popular programming libraries
  6. How to learn programming

1. What is programming?

Programming is simply the process of writing computer programs. Essentially, developers write words and symbols that tell a computer what they want it to do.

Just like humans can understand specific languages (English, French, German, Spanish, etc.), so can computers. 

There are many different kinds of programming languages, and each serves a particular purpose. Some programming languages are designed for speaking to web browsers, others communicate with servers, and a few work within native operating systems like Android phones or Apple computers, like such as Swift.

2. What is a programming library?

A programming library is a collection of prewritten code that programmers can use to optimize tasks.

This collection of reusable code is usually targeted for specific common problems. A library usually includes a few different pre-coded components. 

3. How do developers use libraries?

Developers use libraries to build apps and websites more efficiently. Each library is designed to provide a solution to a specific feature. This can include user authentication, server connection, user interfaces, data management, algorithms, animations, etc. 

Developers will often look up libraries to help with a particular component they want to create quickly or are struggling with. Then, they’ll choose the components they want to use all from that one library, so their app is as cohesive as possible. 

Sometimes developers will also use libraries to view what they’re working on from a different perspective. Every coder does things a little bit differently. Developers can refer to libraries to see how they might be able to do something in a different manner. 

4. What’s the difference between a library and a framework?

The words “framework” and “library” are often used synonymously.

But, most programmers would argue that they’re actually two different things. You could think of it this way: the framework is a model house, and a library is the flat-pack furniture and decor that goes inside

In most instances, a library is a collection of objects and functions that can be used individually and must be configured to work together. Libraries focus on solving a specific problem within an area of development. Libraries allow you to dictate the flow of an application, add custom code, and quickly add only components that you need. 

Frameworks are often more like blueprints. Frameworks are collections of coded components that are already configured to work together. Frameworks generally include a preset architecture or design that developers must work within.

Frameworks often focus on functioning as an all-in-one solution for a specific methodology. 

A model house doesn’t have many custom choices. It’s based on a predetermined blueprint and standard options. On the other hand, Ikea has tons of options and customizations for its easy-to-build furniture.

5. Popular programming libraries

There are libraries for every programming language. Libraries are most commonly used by data scientists and web developers.

Just like the most popular coding languages may not be the best one for you, so too does it depend on what you want to achieve.

Most popular programming libraries

First, we’ll list the most popular programming languages in the world, which are primarily data science libraries.


NumPy is a Python library that developers can use to make powerful arrays. This library is used for machine learning.

NumPy helps developers simplify their work by sorting through massive amounts of data in less time. 


Another Python library, Matplotlib is often used with NumPy to make datasets more manageable. It also serves up standard graphing functions that can be used to visualize data on a timeline. 


TensorFlow can be used with Python or C++. It was developed by Google to help create and train machine learning models. It’s mainly used for neural networks. 

Apache Spark

Apache Spark is an analytics engine for big data processing. It’s designed for Scala, Python, Java, and SQL. Spark supports super fast analytic queries against large amounts of data.  

Best JavaScript libraries

Because JavaScript has been so pivotal for full-stack web development, it’s worth taking a look at the tools it uses. We’ll touch on the most popular JS libraries, but it’s important to learn vanilla JavaScript first.

Getting started is easier than you think, with this free online video tutorial from our in-house web developer Abhi:


Node.js was created to help developers build scalable network apps. It’s a server environment that can run on almost any operating system, including Windows, Linux, Unix, or Mac OS X.

Node allows developers to program backend functions in JavaScript–a frontend language. It’s often used to open a file on the server and return the content to the client.

If you’d like to learn more about it, check out our full guide to Node.js.


React was created to help developers build web app user interfaces (UIs). It’s maintained by Meta (formerly Facebook).

While it’s simply a collection of UI components, however, sometimes, it’s called a framework because many frameworks are built on React. Learn more about it in our beginner’s guide to React.


Vue offers a component-based collection of templates for fast and efficient app creation. It requires fewer lines of code than many other libraries that perform comparable tasks.

Kind of like the Flask framework for Python, it’s designed to create small apps quickly. 


jQuery simplifies JavaScript programming, and it’s easy to use. It is helps web pages load faster. jQuery provides components for CSS manipulation, animations, and AJAX. It handles browser compatibility issues on its own.

We’ve created a handy guide for jQuery and JavaScript if you want to dive deeper.


p5 is one of the most notorious JavaScript libraries. It was built for creative programming.

It’s a library for beginners that keeps designers, artists, and educators in mind. p5 helps developers simplify the creation of interactive visuals with code. 


Polymer makes it possible for developers to reuse HTML elements.

This is created by Google and GitHub. Developers can also use it to create custom elements using HTML, CSS, and JS to build more interactive applications.

It’s often used alongside Node js. You can learn more about it on the official Polymer website.

Dojo Toolkit

Dojo Toolkit is a modular library created to make the rapid development of cross-platform apps and websites easier. It’s often used to build unique user interfaces. 

6. How to learn programming

As you can see, programming libraries are different from frameworks, but they’re also incredibly useful.

They can aid developers in creating applications more quickly with pre-written lines of code. Libraries generally aim for efficiency, but it’s up to the developer to ensure their use is also effective. 

Ready to try your hand at implementing a programming library? First, you should learn how to program with HTML, CSS, and JavaScriptThen, you can build an app with a library!

Most beginners start with a JavaScript library like p5 or Node.js.

7. Final thoughts

A lot of what seems scary about programming from the start is all of the terminology—all of the abbreviations and confusing terms. Once you start to tackle them one-by-one, you’ll be well on your way to getting comfortable.

As we’ve seen, libraries as a coding term can vary a little, but if you keep thinking of them as flat-pack furniture in the model house that is a framework, it should help.

If you’d like to read a little more about the world of web development, check out these articles:

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