【Information Studies I】 Information Communication Networks and Data Utilization: Study Notes
Hello everyone! In this chapter, we’re going to learn about the mechanisms that power the internet and smartphones we use every day. You might feel intimidated by the word "network," but it’s actually quite similar to the "roads" and "postal systems" we use in our daily lives.
You might be surprised by the number of technical terms at first, but let's go through them one by one, building up a mental picture as we go! Don't worry—you'll definitely be able to master this.
1. How Information Communication Networks Work
Types of Networks: LAN vs. WAN
Networks are broadly categorized by their size (range):
1. LAN (Local Area Network): A network within a limited, small area, such as a school or your home.
2. WAN (Wide Area Network): A wide-area network that connects LANs together, typically using lines provided by telecommunications carriers.
Tip: Think of your home Wi-Fi as a LAN, and the internet—which connects the whole world—as a massive collection of WANs.
What is a Protocol?
For computers to communicate with each other, they need a common set of "rules." These rules are called protocols.
For example, if one person only speaks Japanese and the other only speaks English, a conversation can't happen. Computers are the same; they need to pre-agree on rules like "in what order to send data" or "what to do if an error occurs."
The most important protocol on the internet is TCP/IP:
・TCP: Ensures the reliability of data (checks if the data is intact).
・IP: Delivers data to the correct destination.
【Did You Know?】 The Layered Structure of Protocols
Network rules are divided into "layers" based on their roles. This is to ensure that changing one rule doesn't mess up the rest of the system. It’s just like how you can prepare the "side dishes," "rice," and "container" of a bento box separately!
2. Internet Mechanisms and Identification
IP Addresses: The Address on the Net
Every device connected to the internet is assigned a number called an IP address. Think of this as an "address" on the internet.
・IPv4: Represented as 4 groups of numbers, such as 192.168.0.1 (allows for about 4.3 billion addresses; currently running short).
・IPv6: A new standard created to resolve the IPv4 shortage (can create almost an infinite number of addresses).
Domain Names and DNS
It's hard for humans to remember IP addresses that are just strings of numbers, right? So, we use human-friendly names like "google.com." These are called domain names.
The system that translates domain names into IP addresses is called DNS (Domain Name System).
Analogy: DNS is like the "contacts list" on your phone. When you press a name (domain name) like "Tanaka-kun," it automatically connects you to his "phone number" (IP address).
How the WWW (World Wide Web) Works
This is the system we use to view websites through a browser:
・HTTP / HTTPS: The protocol used by web browsers and web servers to exchange data. The "S" in HTTPS stands for Secure, meaning the communication is encrypted.
・HTML: The language used to create web pages.
・URL: The way we write down the location of information on the web (the address itself).
3. Basics of Information Security
When using a network, "defensive" technology is essential.
1. Encryption: Converting data into an unreadable state so that if it is stolen, the contents remain unknown.
2. Public Key Cryptography: A system where you lock data with a "key anyone can have (public key)" and unlock it only with "a key you keep for yourself (private key)."
3. Firewall: A "protective wall" that prevents unauthorized access from the outside.
Common Misconception: "Encryption makes it 100% safe" is not necessarily true. Your own "personal awareness"—like managing your passwords and not clicking on suspicious links—is just as important!
4. Data Utilization and Databases
What is a Database (DB)?
A collection of information organized to manage and search large amounts of data efficiently is called a database. The most commonly used type today is the Relational Database (RDB), which manages data in the form of "tables."
Data Formats
・CSV format: A text format where data is separated by commas (,). A convenient format readable by most software.
・SSV format: A format where data is separated by spaces.
Data Analysis Process
To use data effectively, you need more than just gathering it; you need to follow these steps:
1. Determine the goal: Decide what you want to find out.
2. Collection: Gather the necessary data.
3. Data Cleansing: The task of fixing duplicates, errors, and inconsistent formatting (like "October 1st" vs. "10/1"). ← This is the most important and difficult part!
4. Analysis: Creating graphs or calculating statistics.
5. Interpretation: Thinking about what the results actually mean.
【Key Point】 The 3 Vs of Big Data
"Big Data," which you hear about often these days, has three main characteristics:
1. Volume: It is simply huge.
2. Variety: It comes in many forms, such as videos, GPS data, and text.
3. Velocity: It is updated in real-time at high speed.
Summary: Key Points of This Chapter
・Communication requires a common rule called "protocols (TCP/IP)"!
・IP address is an "address," and DNS is an "address book (converts names to numbers)"!
・"Encryption" and "Authentication" are essential for security!
・The key to successful data utilization is "cleansing (organizing)" before analysis!
You might be overwhelmed by all the terminology at first, but try to be conscious of it next time you browse a website. Think, "Oh, did the DNS just work?" or "It's using HTTPS, so this is encrypted." When you connect these concepts to your daily life, they will stick in your mind surprisingly well! You've got this!