| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| database/sql | Package sql provides a generic interface around SQL (or SQL-like) databases. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| io/fs | Package fs defines basic interfaces to a file system. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| testing | Package testing provides support for automated testing of Go packages. |