FTP stands for file transfer protocol. This is a way to connect to a server and mass upload or download from a computer or workstation to or from the server. Website designers use this to load complete websites that have been made on a workstation with a software development kit (SDK).
FTP is typically connected by adding the DNS IP address into the FTP software and connecting the computer to the DNS. FTP makes it easy to see all of the files on a server. It also makes it simple to update, delete, or manipulate files in any way necessary by the administrator.
One of the advantages of using FTP is that it makes it much faster to upload the files to the server. Once opened and connected to the server the FTP software has the ability to mass upload files. This means that all of the images and content for a website can be uploaded in a matter of minutes instead of taking hours to upload them the old fashioned way one at a time.
FTP also makes it easy to communicate and send information back and forth from one work station to another using the server. For example, you have one employee on one side of the country working on a website build and you have another employee that is on the other side of the country that needs some of the files from the first employee.
The first employee can upload all those files onto the server and the second employee can have instant access to those files to be able to work them in the way required for his/her part of the website build.
For example you have an image implementation professional (Employee #1) and a website developer (Employee #2). They have separate jobs, but are working on the same website build project. Employee one is responsible for creating backgrounds, header, footer, and other content images.
Employee #1 will upload those images once completed to the server in a designated file and then Employee #2 will then be able to have access to those images to configure them on the website where their final placement will be.