Total Cost of Ownership (TCO) is the calculation of the real cost of software, not just the license fee. For Open Source, it is the sum of: License (usually $0) + Infrastructure (Hosting) + Maintenance (Engineering Hours) + Security Ops.
The "Bus Factor" is a risk metric that asks: "If the lead maintainer gets hit by a bus (or gets hired by a competitor) tomorrow, will this project survive?" It measures how dependent a project is on a single individual versus a diverse group of contributors.
Data Portability refers to the ability to easily export your data from a system in a standard, usable format (CSV, JSON, SQL Dump) and import it into another tool. It is your "Emergency Exit" strategy.
"Open Core" is a business model where the core functionality of the software is free (Open Source), but critical "Enterprise" features (SSO, Audit Logs, High Availability) are proprietary and locked behind a paid license.
This software is owned by a neutral non-profit organization (like The Linux Foundation, CNCF, or Apache), not a single for-profit company. The Intellectual Property (IP) is held in trust for the public.
The project is open source, but the copyright and roadmap are controlled 100% by a single for-profit company (e.g., Vercel, MongoDB Inc., Hashicorp). They effectively dictate the future of the software.