Request for comments are a series of documents which define standards for all sorts of different technologies, such as video streaming, wireless internet transmission protocols, etc.
RFC 1918 describes Address Allocation for Private Internets, an important concept for testing and addressing on internal networks. A similar concept does not yet exist as of 2024-04-09. IANA has stated that a preferred top-level domain for private use should be .INTERNAL. However, this was only provisional. The link above shows a public comment section on why .INTERNAL should or should not be used for this purpose. It has already been closed, and the report is due April 12, 2024.
Currently, about 95% of the internet traffic depends on submarine fiber-optic cables which run across the ocean floor. Many of them are comissioned by large corporations, such as Google, Amazon, Facebook and Microsoft. They are placed under the sea floor by ships which carry large spools of reinforced cables. These cables contain the fiber-optics, aswell as a copper shell for powering optical signal amplifiers along the way.
Interactive, real time submarine fiber-optic cables information (terrestrial fiber optics cables information are corporate secrets): https://submarinecablemap.com
Current "highest-capacity submarine cable in the world" (200 terabits per second), MAREA, owned and funded by Microsoft: https://en.wikipedia.org/wiki/MAREA
A project aiming to bring technology, research and economical development to the Amazonian rainforest to the benefit of the local population while maintaining the biodiversity and climatic conditions of the rainforest.
Projeto Amazônia 4.0 (pt_BR): http://www.iea.usp.br/pesquisa/pesquisadores-colaboradores/projeto-amazonia-4.0
Intended for connecting the brazillian army units located in the eastern amazonian region, this project aimed to install a high-velocity network by laying fiber-optic cables in the riverbeds. The project would also benefit local residents, as areas that were previously untouched could make use of the network, increasing digital inclusion.