The situation
Synchronous means that the participants act at the same time: in a video call, on the phone, in a session live online or while editing a document together. Asynchronous means that each acts in their own time and the contributions follow one another, as a message, an email, a comment or a voice note. “Online” on its own leaves open which of the two is meant. That is deliberate, because good cooperation needs both.
On site, the choice between them is often made by the room: people in the same office simply speak to each other. Online, the choice has to be made. That is both effort and opportunity, because whoever chooses deliberately can give each piece of work the form that suits it.
What holds
Synchronous for what lives on immediate back-and-forth. Working at the same time pays off where participants respond to each other directly: getting to know each other, deciding under uncertainty, resolving a conflict, thinking together in a way that feeds on ideas. What counts here is the answer in the moment.
Asynchronous for what needs time for one’s own thinking, even when it emerges together. Reports, drafts, research, reviews and questions whose answer is not urgent. Asynchronous work gives everyone the time they need and leaves a trace that can be read later. It is also fairer to those who do not like to speak off the cuff.
A rhythm. Good cooperation has a beat: synchronous meetings at reliable intervals, asynchronous work in between. The beat follows the task. A project in an intense phase may need a short daily meeting, a reading group one a month. What matters is that everyone knows the rhythm and that it is kept.
Time zones. Across continents, shared time is scarce. Always inviting at the majority’s convenient hour means the same people always work late at night or early in the morning. Rotating times spread the burden more fairly. Where there is hardly any shared window, more moves into asynchronous work, and the synchronous meetings become shorter and more important.
Documentation as memory. What is decided synchronously evaporates unless it is recorded asynchronously. Notes, a list of decisions and a document with the current status are the cooperation’s memory. They let those who were absent catch up, and they prevent the same question from being decided three times.
Transitions. The real skill lies in switching. If a written exchange goes back and forth without getting anywhere, it is time to talk. If a conversation gets lost in detail, it is time to write the question down and ask someone for a proposal. One simple rule has proved itself: after the third round of back and forth, you speak.
Why
The difference lies in whether the other person can cut in. Synchronously, every answer can still change the question. That is where whatever lives on back-and-forth belongs, because the objection comes while there is still time to change course.
Asynchronously, every contribution is finished before the other person sees it. Each can think a thought through before exposing it to objection, and the work is still shared: it moves forward in turns, like an exchange of letters. A good rhythm gives room to both, to the objection in the moment and to the thought that needs time.
The common mistake
Everything synchronous. The calendar is full of meetings in which reports are read aloud, and no uninterrupted time is left for the actual work. The opposite mistake is rarer but no less harmful: a cooperation that consists only of messages, in which nobody hears the others’ voices any more.
Law
Law distinguishes the two forms too. Depending on the legal form, bodies can take decisions in a meeting, including live online, or in writing by circulation; the requirements are set out under Decisions and meetings.
The distinction also matters for teaching. According to a judgment of the Federal Court of Justice (Bundesgerichtshof, BGH) of 5 February 2026 (III ZR 137/25), teacher and learner are not “spatially separated” within the meaning of Section 1(1) no. 1 of the Distance Learning Protection Act (Fernunterrichtsschutzgesetz, FernUSG) as long as teaching takes place synchronously and in both directions and learners can contact the teacher without particular effort. For asynchronous elements, such as pre-recorded videos, the Act may apply. More under Service contract.
Read on: Good practice for working together online · Live online: sound, picture, roles · Online and on site