If you haven't written much code outside of university yet, then you probably won't have heard of the concept, but today package mangers are everywhere. Every language and ecosystem has one. C♯ has Nuget, Javascript has npm and Bower, and Debian has apt. Even PHP now has one, called composer.

If you're thinking something along the lines of "Why do I need someone to take my parcels to the post office for me?", don't worry! I intend to explain what a package manager is and why / when you would want to use one in this post.

How many times have you downloaded a zip of someone else's library, and manually extracted it into your project? Perhaps it inflated the size of your version control repository, and slowed things down. This is just one of the problems that a package manager is designed to solve. Let me explain.

Imagine that you've just built a house. You've got all the walls and floors in place, and all that's left is to call the gas man and get some central heating installed. You call the gas man, and he comes out with his equipment and gets ready to install a brand new central heating system when he asks you about an electricity supply.

Oh, gosh! You totally forgot about that. Then you have to call the electrician and get him to come out and install the electricity supply. When he comes out, he asks whether you've got planning permission... and, well, you get the picture.

Imagine if you could just say "install this library!", and it would install it, handling all the dependencies for you. Imagine if you could store a list of libraries and their versions, such that you don't have to commit all your libraries to version control - saving on space and speeding up your repository. What if you could issue a single command, and all your libraries could be brought up to the latest version? Now, with a package manager, you can!

Most programming languages and operating systems you come across will have one, and it's usually a good idea to make use of it. To end this post, I'm going to list a few common languages, their associated package managers, and a link to a tutorial on how to use it.

• C♯ - Nuget (Visual Studio tutorial)
• Javascript - npm (tutorial, should work for Linux, Mac, and Windows users)
• Ruby - RubyGems (tutorial, Linux users should have the gem command installed already along with Ruby)
• Python - pip (tutorial - pip comes with python on both Linux and Windows. pypi - The Python Package Index. pip installs packages that are in the python package index.
• Debian - apt (tutorial, should work for most Debian-based linux distributions - apt is probably the command behind your software manager gui. Not technically a programming language library package manager, but really useful all the same.)
• PHP - composer (tutorial)

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