| Turning point? |
| Landmark event |
| Important event |
| Numbered marker |
| Centennial, e.g. |
| Rite of passage? |
| Turning 50, e.g. |
| Significant event |
| Notable achievement |
| 21st birthday, e.g. |
| Rite of passage, e.g. |
| Marker of significance |
| Event worth celebrating |
| 50th anniversary, for example |