With projects, you can organize your tasks by topic or milestones and share them with your team. Together you can work on the tasks in this project. For example, the launch of the website. You can collect and work on all tasks related to this topic in the projects. They will give you a better overview.
Projects are only visible to the users you add to the project. But you can also make it public so that everyone from your company has access and can work on the tasks.