| encoding/binary | Package binary implements simple translation between numbers and byte sequences and encoding and decoding of varints. |
| errors | Package errors implements functions to manipulate errors. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| reflect | Package reflect implements run-time reflection, allowing a program to manipulate objects with arbitrary types. |
| regexp | Package regexp implements regular expression search. |
| 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. |