Portable applications are those that do not require any installation on the host machine. These are very good if you cannnot install anything on your machine. In general there are a variety of different portable applications, but you can also run windows from a stick, creating your own desktop, etc., on the go where ever you are. Windows 10 and 11 make it extremely easy to create a Windows environment on a stick (preferably a fast one with a good amount of free space).