| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| sort | Package sort provides primitives for sorting slices and user-defined collections. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| time | Package time provides functionality for measuring and displaying time. |