A networking model/architecture/blueprint is a comprehensive set of documents. Each document describes a small function required for a network, collectively, these documents describe how a network functions.
These documents could be the following:
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Protocol. A set of logical rules that devices must follow to communicate
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Physical requirements. Voltage and current levels on a particular cable, the specific hardware required in a router, specific tech, etc.
These blueprints are set so that people have a framework to follow. It ensures that the network has the right structure and a solid foundation, and that people from different skills like sysadmins, executives, engineers will be able to do their own job without causing problems for other workers.
Its entirely possible to build you own network, write own software and build own networking cards, but it is much easier and simpler to use products that already conform to a well-known networking model.
These days, the world uses one networking model. But it wasn’t always like this. Standardized networking protocols didn’t use to exist. Vendors created the networking protocols suited only their specific product. There was no standard. IBM had their SNA(Systems Network Architecture) model in 1974, other companies had their own proprietary models. Network engineers back then had to know 3-4 of these models and somehow frankenstien a network that could transmit between all models.
TCP/IP came into existance somewhere in the 1990s, and dominated the networking world in the 2000s where it became the primary model.
Although vendor defined proprietary network models often worked well, the benefits of an open, non-vendor affiliated model would be a net positive for the world. The internet depends on the fact that people are connected, its a tool for the people, so by blocking off information about the structure, you would be limiting its potential and breaking the hidden principles and ideologies that the internet stands for. Communications, regardless of location, regardless of opinions, nationality, gender, a free world, maybe a second life to our so terribly fragile current world.
The International Organization for Standardization (ISO) started work on this system in the 1970s. They would begin work on the Open Systems Interconnection(OSI) model with the noble goal to standardize data networking protocols to allow communications between all computers across the entire planet. The OSI was developed with help from technological enthusiasts all across the world.
The U.S Department of Defense had visions also of creating a open standardized model for the world. Creating the DoD model, which later transformed to what we know now as the TCP/IP model
these days, TCP & IP prevails, partly in due of the budget the DoD has. OSI takes a good second place though.
You will probably never encounter a device that uses OSI protocol instead of TCP & IP, but its still good to know the jargon anyhow.