Are there any rules to configure IP addresses when constructing a network by TCP/IP?

IP address is described as below:

IP address is the numbers to identify each machine attached to machines on computer network in simple terms, such as an address and telephone number.

When computers make communication, they recognize each other by the numbers for identification.

Each IP address is allocated to the machines (PC, router, modem, etc.) to access to internet.

You need to follow the rules to set IP address.

[Rule 1]

You need to set IP address to the machines(PC, printers, servers, routers, etc.) which are connected to each network for TCP/IP communication.

[Rule 2]

IP address needs to be unique number on the same network.

[Rule 3]

IP address is composed by two elements as below.

・IP address
・Subnet mask

IP address is the identification number of each machine.
Global IP address which is available only one in the world is directly used for internet. Local IP address is mostly used in separated area from internet by routers and others.

For example, global IP address means to be the location to describe address of an apartment;
The local IP address is the room number of the apartment.
It needs to be a unique number within the network.

[Example]
192.168.11.100

Subnet mask is used to express the range of network.
It shows the number (equals to the range) which is able to belong to the same network.

[Example]

[Example of setting]

When you allocate IP address at general companies/houses using your Buffalo router products, follow the range below.

192.168.11.1～254　/　255.255.255.0

The above rules of IP address is only small part of the rules.
Check TCP/IP books for the detail about IP address.