Problem summary

The user wants to revert a mistaken input.

Solution

Allow users to easily reverse their own actions.

Rationale

Users aren’t perfect – they tend to make mistakes.

Promote safe exploration and playfulness by providing confidence that mistakes aren’t permanent. Multi-level undo lets users incrementally construct and explore work paths quickly and easily. The more costly it is to lose data, the more important it is to provide the opportunity to undo.