what does the word "transform" mean in tf?

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I am new to ROS and as a result was reading about the tf package. I read this paper: http://wiki.ros.org/Papers/TePRA2013_... ; where the author made statements such as "...The request is the same in every case, and the programmer only needs to know the coordinate frames in which they want to operate and those relevant to the task, as long as the system knows the intermediate frames and can compute the resultant transforms.", another one is "The tf library can be separated into two different parts. The first part is disseminating transform information to the entire system. The second part of the library receives the transform information and stores it for later use".

I do not understand the context in which this word is used. My understanding of the word transform is synonymous to the word 'change'. Can you please help me understand the context in which this word is used? I do not understand what "transform information" means, and all other uses of this word in this document. Thanks for your help... this will help me better understand the package.