Azure classic portal (ASM model)
Historically, Azure services were provided via one portal prior to 2014, the classic portal, which can be accessed via the following URL https://manage.windowsazure.com/.
The model that was used for that portal is called the ASM model, within which each resource existed independently. You could not manage your resources together; you had to build up and track each resource. For example, you would have to manage storage from the storage blade, and the same goes for the virtual networks, VMs, and so on. So, when your environment got bigger, there would be chaos in the management scheme. You would have to know which VMs were stored in which storage account, and that could lead to some critical situations, such as reaching the IOPs limits of the storage account. In turn, this could result in you accidentally creating a new VM and assigning it to that storage account. As a result, the VM would run with terrible performance. This would not be your only concern when working with the ASM model; you might want to delete a solution with multiple resources, which you would have to do manually for each resource.
When you open the Azure classic portal, it will look like the following screenshot: