| encoding/binary | Package binary implements simple translation between numbers and byte sequences and encoding and decoding of varints. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| math | Package math provides basic constants and mathematical functions. |
| reflect | Package reflect implements run-time reflection, allowing a program to manipulate objects with arbitrary types. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |