Real-time co-editing transforms collective work on diagrams, solving the classic problems of file exchanges — as big a change as co-editing was for Word/Excel documents. The problem with the old way (exchanging files): traditionally, working with several people on a diagram meant EXCHANGING the FILE: one person creates it, sends it by email, another modifies it and sends it back, etc. Problems: (1) Version CONFLICTS (“who has the latest version?”, multiple versions floating around, changes lost when two people work on copies in parallel). (2) SLOWNESS (sequential back and forth — one waits for the other to finish and send back). (3) CONFUSION (what version is up to date? where are the latest changes?). (4) No SIMULTANEOUS work (one person at a time, otherwise conflicts). This mode is tedious and prone to errors, especially when co-constructing a diagram with several people. What real-time CO-EDITING changes: (1) SINGLE and shared version. The diagram is in the CLOUD (OneDrive/SharePoint), a single version, which everyone has access to. No more multiple copies and version conflicts — there is ONE version, always up to date. (2) SIMULTANEOUS WORK. Several people can modify the SAME diagram AT THE SAME TIME. Everyone sees the modifications of the others LIVE (the cursors, the changes appear in real time). We co-build TOGETHER, in parallel, not sequentially. (3) SPEED and fluidity. No more back and forth of files, no more waiting: we work together, directly. A meeting to build a process/organization chart becomes a real-time co-creation (everyone contributes, we see the result being built). (4) Clarity. Everyone is working on the same updated version — no confusion about “the right version.” The changes are visible to everyone immediately. (5) Teams integration. You can co-edit the diagram directly in Microsoft Teams (the team's collaboration space) — the diagram is where the team works and discusses. How this changes teamwork in concrete terms: (1) CO-CONSTRUCTION. Build a process, an organization chart, a diagram WITH SEVERAL people in real time (everyone adds/modifies, we discuss and adjust together live) — much more effective than passing a file around. Ideal for process mapping workshops, collective design. (2) Collective REVIEW and improvement. Review a diagram together, make changes live, discuss (with comments — section 5-2). (3) REMOTE COLLABORATION: people in different locations co-edit the same diagram in real time (teleworking, distributed teams). (4) Collaborative UPDATE: maintain a shared diagram with several people (each updates their part). The conditions: (1) CLOUD storage (OneDrive/SharePoint) — the diagram must be in the cloud for co-authoring. (2) Use of Visio for the web (or the office connected to the cloud depending on the case). (3) Microsoft 365 environment (sharing, permissions). The parallel with other Microsoft 365 tools: Visio's real-time co-editing follows the same principle as Word, Excel, PowerPoint online - a principle which has transformed the work on documents (no more files exchanged by e-mail). Visio benefits from the same modernization for diagrams. Nuances: (1) Co-editing is mainly done via Visio for the WEB (which does not have all the functions of the office - for very advanced technical diagrams, you may need the office, less collaborative in real time). (2) It assumes Microsoft 365 infrastructure (cloud, accounts). In summary: real-time co-editing transforms teamwork on diagrams by replacing the old way (file exchange — version conflicts, slowness, confusion, no concurrency) with CO-CREATION on a SINGLE VERSION shared in the cloud, where multiple people edit the SAME diagram AT THE SAME TIME, seeing the changes live. This makes it possible to CO-BUILD diagrams with several people in real time (workshops, collective design), to REVIEW together, to collaborate REMOTELY, on a version that is always up to date and without conflicts — all integrated into the team space (Teams). This is a major contribution for collective work on diagrams (frequent: co-constructing a process, an organization chart, a diagram), moving from isolated and tedious work (exchanged files) to fluid collaboration in real time — the same revolution that co-editing brought to documents. An evolution that makes Visio suitable for modern, distributed teamwork.