| bytes | Package bytes implements functions for the manipulation of byte slices. |
| io | Package io provides basic interfaces to I/O primitives. |
| regexp/syntax | Package syntax parses regular expressions into parse trees and compiles parse trees into programs. |
| sort | Package sort provides primitives for sorting slices and user-defined collections. |
| strconv | Package strconv implements conversions to and from string representations of basic data types. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| unicode | Package unicode provides data and functions to test some properties of Unicode code points. |
| unicode/utf8 | Package utf8 implements functions and constants to support text encoded in UTF-8. |