About Go packages

Packages are for grouping related functions and constants so that you can transfer them easily and use them in your own Go programs. As a result, apart from the main package, packages are not autonomous programs.

There exist many useful Go packages that come with each Go distribution including the following:

• The net package: This supports portable TCP and UDP connections
• The http package: This is a part of the net package and offers HTTP server and client implementations
• The math package: This provides mathematical functions and constants
• The io package: This deals with primitive input and output operations
• The os package: This gives you a portable interface to the operating system functionality
• The time package: This allows you to work with times and dates

For the full list of standard Go packages refer to https://golang.org/pkg/. I strongly advise you to look into all the packages that come with Go before you start developing your own functions and packages because there is a realistic chance that the functionality you are looking for is already available in a standard Go package.