class 6

 What is computer virus?

A computer virus is a type of malware that attaches to another program (like a document), which can replicate and spread after a person first runs it on their system. For instance, you could receive an email with a malicious attachment, open the file unknowingly, and then the computer virus runs on your computer. Viruses are harmful and can destroy data, slow down system resources, and log keystrokes.

Windows, Mac, Android, and iOS

Many computer viruses target systems running Microsoft Windows. Macs, on the other hand, have enjoyed a reputation as virus-proof super machines, but in Apple’s own admission, Macs do get malware. There are more Windows users in the world than Mac users and cybercriminals simply choose to write viruses for the operating system (OS) with the largest amount of potential victims. 

Today, the “computer” in our pockets may be the one we use most often: our smartphones. Android and iOS are susceptible to various forms of malware, too. Fortunately, most cybersecurity companies like Malwarebytes offer protection for Windows, Mac, Android, and iOS today. 

Computer virus examples

Sometimes to understand what something is, we have to examine what it isn’t. Keeping that in mind, let’s play: Is It a Virus?

In the Is It a Virus game we’re going to take a look at examples of things people on the Internet commonly believe to be a virus and explain why it is or isn’t. What fun!

Is a Trojan a virus? Trojans can be viruses. A Trojan is a computer program pretending to be something it’s not for the purposes of sneaking onto your computer and delivering some sort of malware. 

History of computer viruses

Today’s malware authors owe a lot to the cybercriminals of yesteryear. All the tactics and techniques employed by cybercriminals creating modern malware were first seen in early viruses. Things like Trojans, ransomware, and polymorphic code. These all came from early computer viruses. To understand the threat landscape of today, we need to peer back through time and look at the viruses of yesteryear.

1984, Computer virus, defined
In 1984 computer scientist Fred Cohen handed in his graduate thesis paper, Computer Viruses – Theory and Experiments in which he coined the term “computer virus,” which is great because “complicated self-reproducing automata” is a real mouthful. In the same paper, Cohen also gave us our first definition of “computer virus” as “a program that can ‘infect’ other programs by modifying them to include a possibly evolved copy of itself.”

1999, “You’ve got mail (and also a virus)”
Think back to 1999. If someone you knew sent you an email that read “Here is the document you requested … don’t show anyone else ;-),” you opened the attachment.

This was how the Melissa virus spread and it played on the public’s naiveté about how viruses worked up to that point. Melissa was a macro virus. Viruses of this type hide within the macro language commonly used in Microsoft Office files. Opening up a viral Word doc, Excel spreadsheet, etc. triggers the virus.

How Does the Internet Work? 

An internet is a huge network of networks that helps us to connect millions of computers together. These computers that are connected to each other through the internet can interact with each other over the internet.

The Internet operates on a technique called packet switching. In packet switching, the data that is transferred among the different computers on the internet are transmitted in the form of packets. These packets contain information about the error control mechanisms, the address of the destination, and also the sequence in which the packets are to be transmitted.

What happens when we surf the Internet?

1. Extracting IP address of a URL (Uniform Resource Locator) In our browser, we enter the URL (Uniform Resource Locator) address of the website we want to visit. Once we enter the URL address of the website, the browser with the help of the DNS (Domain Name System) extracts the IP address corresponding to the URL address that is entered. The DNS (Domain Name System) contains the mapping of the URLs along with their corresponding IP addresses.

2. Sending request to the server to access the webpage and receiving response Once we get the IP address of the website we want to access using DNS, the browser sends an HTTP (Hypertext Transfer Protocol) request to the server to extract the HTM (Hypertext Markup Language)L webpage corresponding to the IP address. This request is sent over PORT 80 using TCP (Transmission Control Protocol). Once the server receives this HTTP request, it responds back with an HTTP response. This HTTP response consists of the information related to the HTML page corresponding to the IP address of the website.

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class 8

 What is the Internet?

The Internet is a global network of billions of computers and other electronic devices. With the Internet, it's possible to access almost any information, communicate with anyone else in the world, and do much more.

You can do all of this by connecting a computer to the Internet, which is also called going online. When someone says a computer is online, it's just another way of saying it's connected to the Internet.

What is the Web?

The World Wide Web—usually called the Web for short—is a collection of different websites you can access through the Internet. A website is made up of related text, images, and other resources. Websites can resemble other forms of media—like newspaper articles or television programs—or they can be interactive in a way that's unique to computers.

Social networking

Social networking websites are another way to connect and share with your family and friends online. Rather than sharing with just a few people over email, social networks make it easier to connect and share with many people at the same time. Facebook is the world's largest social networking site, with more than 1 billion users worldwide.

Chat and instant messaging

Chat and instant messaging (IM) are short messages sent and read in real time, allowing you to converse more quickly and easily than email. These are generally used when both (or all) people are online, so your message can be read immediately. By comparison, emails won't be seen until recipients check their inboxes.

Examples of instant messaging applications include Yahoo Messenger and Google Hangouts. Some sites, like Gmail and Facebook, even allow you to chat within your web browser.

Online media

There are many sites that allow you to watch videos and listen to music. For example, you can watch millions of videos on YouTube or listen to Internet radio on Pandora. Other services, like Netflix and Hulu, allow you to watch movies and TV shows. And if have a set-top streaming box, you can even watch them directly on your television instead of a computer screen.

Basics of Computer Networking

Computer Networking is the practice of connecting computers together to enable communication and data exchange between them. In general, Computer Network is a collection of two or more computers. It helps users to communicate more easily. In this article, we are going to discuss the basics which everyone must know before going deep into Computer Networking.

Basic Terminologies of Computer Networks

• Network: A network is a collection of computers and devices that are connected together to enable communication and data exchange.
• Nodes: Nodes are devices that are connected to a network. These can include computers, Servers, Printers, Routers, Switches, and other devices.
• Protocol: A protocol is a set of rules and standards that govern how data is transmitted over a network. Examples of protocols include TCP/IP, HTTP, and FTP.
• Topology: Network topology refers to the physical and logical arrangement of nodes on a network. The common network topologies include bus, star, ring, mesh, and tree.
• Service Provider Networks: These types of Networks give permission to take Network Capacity and Functionality on lease from the Provider. Service Provider Networks include Wireless Communications, Data Carriers, etc.
• IP Address: An IP address is a unique numerical identifier that is assigned to every device on a network. IP addresses are used to identify devices and enable communication between them.
• DNS: The Domain Name System (DNS) is a protocol that is used to translate human-readable domain names (such as www.google.com) into IP addresses that computers can understand.
• Firewall: A firewall is a security device that is used to monitor and control incoming and outgoing network traffic. Firewalls are used to protect networks from unauthorized access and other security threats.

What is Visual Basic?

Visual Basic is a third-generation event-driven programming language first released by Microsoft in 1991. It evolved from the earlier DOS version called BASIC. BASIC means Beginners' All-purpose Symbolic Instruction Code. Since then Microsoft has released many versions of Visual Basic, from Visual Basic 1.0 to the final version Visual Basic 6.0. Visual Basic is a user-friendly programming language designed for beginners, and it enables anyone to develop GUI window applications easily.

The Visual Basic 6 Integrated Development Environment

Before you can write programs in VB 6, you need to install Visual Basic 6 compiler on your computer. You can purchase a copy of Microsoft Visual Basic 6.0 Learning Edition or Microsoft Visual Basic Professional Edition from Amazon.com, both are vb6 compilers. Besides, you can also buy it from eBay at Microsoft Visual Basic 6.0 6 Professional PRO MSDN Library Manual Service Pack. If you have already installed Microsoft Office in your PC or laptop, you can also use the built-in Visual Basic Application in Excel to start creating Visual Basic programs without having to spend extra cash to buy the VB6 compiler.

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class 7

What is flashes logo?

Allen was a scientist who gains his power after being struck by lightning, which granted him superspeed. He named himself The Flash after his hero Jay Garrick, with his emblem being a lightning bolt in the center of his red costume.What does Flash symbol mean?

The official colors were: a white lightning bolt ("flash") and circle, a blue roundel, and a red background. The symbolism of this design was meant to convey a flash of action within a circle of unity.
Introduction:- 
Electronic mail, commonly known as email, is a method of exchanging messages over the internet. Here are the basics of email:

1. An email address: This is a unique identifier for each user, typically in the format of name@domain.com.

1. An email client: This is a software program used to send, receive and manage emails, such as Gmail, Outlook, or Apple Mail.

1. An email server: This is a computer system responsible for storing and forwarding emails to their intended recipients.

           To send an email:

1. Enter the recipient’s email address in the “To” field.
2. Add a subject line to summarize the content of the message.
3. Write the body of the message.
4. Attach any relevant files if needed.
5. Click “Send” to deliver the message to the recipient’s email server.
6. Emails can also include features such as cc (carbon copy) and bcc (blind carbon copy) to send copies of the message to multiple recipients, and reply, reply all, and forward options to manage the conversation.

Advantages of email:

• Convenient and fast communication with individuals or groups globally.
• Easy to store and search for past messages.
• Ability to send and receive attachments such as documents, images, and videos.
• Cost-effective compared to traditional mail and fax.
• Available 24/7.
• Risk of spam and phishing attacks.
• Overwhelming amount of emails can lead to information overload.
• Can lead to decreased face-to-face communication and loss of personal touch.
• Potential for miscommunication due to lack of tone and body language in written messages.
• Technical issues, such as server outages, can disrupt email service.
• It is important to use email responsibly and effectively, for example, by keeping the subject line clear and concise, using proper etiquette, and protecting against security threats.

What is QBasic Class 7 short note?

QBasic is an integrated development environment (IDE) and interpreter for a variety of dialects of BASIC which are based on QuickBASIC. Code entered into the IDE is compiled to an intermediate representation (IR), and this IR is immediately executed on demand within the IDE.

Write any four features of QBASIC.

Ans: Four features of QBASIC are:

QBASIC has many features. Some features of QBASIC are given below.

QBASIC is interpreter based language, so it is easy to debug.

QBASIC checks syntax automatically

QBASIC supports various inbuilt functions.

QBASIC supports modular programming approach.

QBASIC is not case sensitive so, can be used in any case of letters.

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