Jupyter notebooks are useful for sharing insights about data. If the notebook is just on your own device, how are you supposed to share it? Sending an ipynb file to someone else is not a great experience. Ideally, you could send a link, and the recipient doesn’t have to worry about installing Jupyter or Python environments or anything like that.
A difficult way to do this is to run JupyterHub and expose it to the internet. It’s a lot of effort, but valid in some situations. If only you need to access it, running Jupyter in server mode is slightly easier. Both of these options require you to run a server such as a machine on a cloud service like AWS.
Managed, or hosted, notebooks such as Deepnote are a much more reliable way to do this. Managed notebooks handle running Jupyter for you, and let you share notebooks with just a link. Setting them up takes minutes instead of hours.