Computing Concepts and the Internet

Computing Concepts & The Internet

• An algorithm is a step-by-step set of instructions designed to solve a problem.
• Abstraction simplifies complex systems by dividing them into layers or concealing intricate details.
• Binary is a base-2 number system that uses only 0s and 1s.
• A bit is the smallest unit of data in computing, represented as either 0 or 1.
• A byte consists of a group of 8 bits.
• An overflow error occurs when a numerical value exceeds the system's capacity to handle it.
• Lossy compression reduces file size by permanently removing some data. JPEG is an example.
• Lossless compression reduces file size without any data loss. PNG and ZIP files are examples.
• Packets are small segments of data transmitted across networks.
• An IP Address is a unique identifier assigned to each device on a network.
• DNS (Domain Name System) translates domain names like google.com into IP addresses.
• TCP/IP (Transmission Control Protocol/Internet Protocol) are protocols governing packet delivery over the internet.
• HTTP/HTTPS (HyperText Transfer Protocol/Secure) are protocols used for transmitting web data.
• DDoS (Distributed Denial of Service) attacks flood a server with excessive traffic.
• Phishing is a cyberattack that employs deceptive emails or websites to steal personal information.
• The digital divide refers to the disparity in technology access between different groups.

Data & Information

• Metadata is data providing information about other data, which includes file size and resolution.
• Big data refers to extremely large datasets utilized for in-depth analysis and informed decision-making.
• Machine learning involves algorithms that enable computers to learn patterns from data.
• Encryption is the process of encoding data to ensure its security.
• Decryption reverses the encryption process, restoring data to its original form.
• Public key encryption employs separate keys for encryption (public key) and decryption (private key).
• Symmetric encryption uses the same key for both encryption and decryption.
• ASCII (American Standard Code for Information Interchange) is a character encoding standard.
• The ASCII value of '5' is 53, as an integer.
• The operation '5'-'0' results in 53 - 48 = 5.
• If char c = 'B'+32, then c stores 'b'.

Programming Fundamentals

• A variable is a named storage location that holds a value.
• Data type specifies the kind of data a variable can store, which include integers, strings, and booleans.
• A string is a sequence of characters enclosed in quotes, such as "Hello".
• Boolean is a data type with two possible values such as true or false.
• Conditional statements (if, else, elif) are used to execute different code blocks based on specific conditions.
• For loops repeat a set of instructions a specified number of times.
• While loops repeat a set of instructions as long as a condition remains true.
• Functions are reusable blocks of code designed to perform specific tasks.
• A list/array is a collection of elements stored in a specific order, accessible by an index.
• The index is the position of an item in a list, starting from 0.
• The modulus operator (%) returns the remainder of a division operation.
• Concatenation is the process of joining two or more strings together.

Global Impact of Computing

• Crowdsourcing involves collecting data or contributions from a large group of people, such as in Wikipedia.
• Open-source software is software with freely available source code that can be modified and distributed.
• Intellectual property refers to creations of the mind, such as inventions, literary, and artistic works. These are protected by law through, for example, patents and copyrights.
• Bias in computing arises when algorithms or data unfairly favor certain groups.

Java Programming Basics

• Java is a high-level, object-oriented programming language.
• A class serves as a blueprint for creating objects in Java, defining their structure and behavior.
• An object is an instance of a class, possessing attributes and behaviors.
• A method is a function within a class that defines specific behaviors.
• A constructor is a special method used to initialize objects when they are created.
• An instance variable is a variable defined inside a class, unique to each object instance.
• A static variable is shared among all instances of a class.
• Primitive types in Java include int, double, boolean, and char.
• Reference types in Java include String, Array, and Object.
• Casting is the process of converting a value from one data type to another.

Control Structures & Logic

• Relational operators are used to compare values (==, !=, >, <, >=, <=).
• Conditional statements (if, else if, else) allow the execution of different code blocks based on specified conditions.
• Loops (for, while) are used to repeat a block of code multiple times.
• Arrays are used to store collections of elements of the same data type.
• ArrayLists are dynamic arrays that can grow or shrink as needed.

Object-Oriented Programming (OOP)

• Encapsulation involves bundling data and methods that operate on that data within a class.
• Inheritance allows a class to inherit properties and methods from another class.
• Polymorphism enables objects of different classes to be treated as objects of a common type.
• Abstraction involves simplifying complex systems by breaking them down into smaller, manageable parts.

Algorithms & Data Structures

• Searching algorithms are used to find a specific element in a collection of data.
• Sorting algorithms are used to arrange elements in a specific order (e.g., ascending or descending).
• Data structures are ways of organizing and storing data, such as arrays, linked lists, stacks, and queues.
• Recursion is a technique where a function calls itself to solve a problem.

Software Development

• Software development life cycle (SDLC) is a process for planning, creating, testing, and deploying software.
• Debugging is the process of identifying and fixing errors in code.
• Testing is the process of verifying that software meets specified requirements.
• Documentation is the process of creating written materials that describe how software works.

JavaScript Programming

• JavaScript is a high-level, interpreted programming language primarily used for front-end web development.
• Variables are declared using var, let, or const.
• Data types include strings, numbers, booleans, objects, arrays, null, and undefined.
• Functions are blocks of code that can be defined and called by name.
• Objects are collections of key-value pairs.
• Arrays are ordered lists of values.
• DOM (Document Object Model) is an interface for interacting with HTML and XML documents.
• Events are actions or occurrences that happen in the browser, such as clicks, mouseovers, and keypresses.
• Asynchronous programming allows JavaScript to perform tasks in the background without blocking the main thread.
• AJAX (Asynchronous JavaScript and XML) is a technique for updating parts of a web page without reloading the entire page.

Using APIs

• APIs (Application Programming Interfaces) allow different software systems to communicate with each other.
• Fetch API provides an interface for fetching resources, including making HTTP requests.
• JSON (JavaScript Object Notation) is a lightweight data-interchange format that is easy for humans to read and write.

Topics in JavaScript Code

• An image object contains metadata such as filename, size, and resolution.
• Extracting metadata can be done by accessing the object's properties, such as image.size, which outputs "2MB".
• The Caesar cipher encryption shifts each letter by a fixed number of positions in the alphabet.
• The example Caesar cipher shifts each character by 3 positions, so "hello" becomes "khoor".
• Variables can store different data types, such as strings ("Alice"), numbers (25), and booleans (true).
• Conditional statements (if-else) execute different code blocks based on conditions.
• Loops (for and while) repeat code blocks multiple times.
• For loops iterate a specific number of times shown in the example with the variable i which runs from 1 to 5, inclusive.
• While loops continue as long as a condition is true shown in the example with the variable count which increments to 5.