There are three types of IP related design terms which came to me while studying the CCNA which are
Subnetting is the process of having an IP address and divided it between two or more networks.
-----------------Classless inter-domain routing (CIDR) is the process of identifying how many bit notations are there in an IP address for example a /24 bit notation.
Variable length subnet masks (VLSM) which is a similar process as the Subnetting. However it involves more work in order to increase the sufficiency of the network, by eliminating any IP addresses being wasted or keep the waste to a minimal.
For example in a peer-to-peer links such as a connection between two routers we would use the /30 bit notations instead of using a whole class address.
You can refer to the links below for more information, sorry for writing my answer in English as I don't have access to an Arabic keyboard at the moment.
note: what I have written above represent the way that I understood the three terms it could be right and could be wrong but if you want more technical and accurate it information visit the links