Hello there is not only the Clear Web (Google, Facebook, Youtube, etc) but also an infinite number of private, anonymous and decentralized networks accessible through specific software.
Let's see the main ones.

TOR (The Onion Router) is a software based on the Vidalia interface that allows you to surf anonymously on the internet.
It relies on Firefox and can be integrated into VPN.
Link type: Onion

FREENET is different from most peet to peer software.
The network is made up of several nodes, which influence the size of the network.
These nodes transmit messages to each other.
Usually a host computer connected to the network (running the software) acts as a node and connects to other hosts to form a large distributed network of peer nodes.
Some nodes are end users, others are only used to route data.
All nodes communicate with each other identically there are no dedicated "clients" or "servers".
It is not possible to classify or otherwise differentiate the various nodes, except for their ability to insert and retrieve the data associated with a key.
In short, there are no structures or hierarchies. Link type: Localhost

ZERONET is a decentralized network based in Budapest (Hungary).
The network is programmed in Python and is completely open source.
The sites are accessible with any web browser as long as you use the ZeroNet application, which acts as a local provider for these pages.
You can install it on both Windows and Linux and OS X.
What can I find on it? Blogs, forums, web space (hosting), files for download, chat, mail and more.
The connections to the sites will always be fast as they will be downloaded to your PC (becoming your own Host) making them accessible even offline (like Freenet).

ANONET is a decentralized network built using VPN and routing protocols (BGP used to connect multiple autonomous routers together).
In some ways it is a Darknet (sites are not indexed on google) of the Friend To Friend type because the connections take place between users who "know each other".
In a nutshell the network is by invitation and we could define it "pseudo-anonymous".
RSA passwords and digital signatures are used for network authentication.

I2P (Invisible Internet Project) is an Open Source software for the creation of an anonymous network.
I2PTunnel is an application incorporated in I2P that allows TCP / IP applications to communicate on I2P through the creation of a "tunnel", which can be accessed through a specific port on localhost.
Any Bittorrent client can take advantage of the I2P network for its functionality, simply by configuring the client and browser and downloading the .torrent file.
I2P has a built-in application called I2PSnark.

OSIRIS is a free italian software, the purpose of which is to allow anyone to create and maintain a "peer-to-peer" website, that is, without resorting to a central server, without paying the rent to a manager, without the need for register and be registered as site owners. The idea is to create anonymous sites with P2P technology.

ALIENET is a private and closed, therefore hidden network developed by "The Darknet Project".
In some ways the operation is similar to the TOR network with the difference that a VPN is automatically implemented here.
The VPN client used is OPENVPN.
You also need to download an encrypted key.
The only information that Alienet needs to identify the client on the network is the assigned IP and the PEM key, encrypted at 2048 bits.
The server that receives the request for access completely disregards the IP of the applicant but regulates access only on the basis of the encrypted access key held by the applicant.

HYPERBORIA is a global decentralized network of "nodes" that works through the Cjdns or Phantom software.
Cjdns uses a TUN device, all Cjdns addresses represent the first 16 bytes (128 bits) of the double SHA-512 (public key).
All addresses must start with the 0xFC byte, which in IPv6 resolution is a private address (so there is no conflict with Internet IP addresses).
Once the node is set, the address is generated by brute force techniques (until the result is exactly twice the SHA-512 and starts with 0xFC).
All this guarantees encrypted addresses from random data (the private key is random, the public key is the scalar multiplication of this random data).
The idea is to have each node connected directly with physical means: wires, cables or radio waves.

USENET is a worldwide network made up of interconnected servers, each of which collects articles (news, messages, posts) that people with access to that server send themselves (in a public archive that can be consulted by all subscribers).
Usenet is organized into thematic hierarchies and newsgroups (threads) of articles on the same theme.
Usenet was launched in 1979 in Duke University.
To connect to the Usenet network, you first need a subscription to an NSP server.

First communications networks in history: ARPANET, FIDONET, NPL, CYCLADES, CERNET, FOCUS, INDEX, SNA, DECNET, VNET, BERKNET, UUCPNET, BITNET, INFN, GARR, IUNET, EUNET

Military Networks: MILNET, DDN, SIPRNET, NIPRNET, JWICS, GWAN, CRONOS, RIPRNET

Intranet: HALAL Internet