| bytes | Package bytes implements functions for the manipulation of byte slices. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| image | Package image implements a basic 2-D image library. |
| image/color | Package color implements a basic color library. |
| io/ioutil | Package ioutil implements some I/O utility functions. |
| log | Package log implements a simple logging package. |
| net/http | Package http provides HTTP client and server implementations. |
| net/url | Package url parses URLs and implements query escaping. |
| path/filepath | Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths. |
| runtime | Package runtime contains operations that interact with Go's runtime system, such as functions to control goroutines. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |