Bus Factor

The Bus Factor highlights the human single point of failure in projects. In many software teams, one or two people might understand the legacy system, a crucial algorithm, or have all the deployment knowledge. If those people leave, others cannot easily pick up the work.

The concept encourages actively avoiding such dependency. Improving bus factor overlaps with knowledge management practices: pair programming, code reviews, documentation, mentorship, and rotating responsibilities.

• A bus factor of 1 means one person holds critical knowledge; if they disappear, the project is essentially 'doomed' or stalled. A higher bus factor (e.g., 5) means the project could lose any one of five specific people before stopping work.
• It's basically a measure of knowledge distribution and risk. A high bus factor is good (knowledge is shared among many), while a low is bad (single points of failure in expertise).
• Teams should work to increase their bus factor by sharing knowledge, documenting critical systems, having code reviews, and rotating responsibilities.