Module 2

• Data


  Unprocessed numbers, or facts
• Information


  Processed data that becomes meaningful
• Knowledge


  Information that is understood and used by people for different purposes
• Data representation


  The form in which data is stored, processed and transmitted
• Digital devices

  • Store data using the binary number system
• Bit


  A single unit of binary data, either 0 or 1
• Byte


  8 bits combined together
• Data storage units

  • Bit
  • Byte
  • Kilobyte
  • Megabyte
  • Gigabyte
  • Terabyte
  • Petabyte
• 1 Kilobyte = 1024 Bytes
• 1 Megabyte = 1024 Kilobytes
• 1 Gigabyte = 1024 Megabytes
• 1 Terabyte = 1024 Gigabytes
• 1 Petabyte = 1024 Terabytes
• Bits and bytes also store information about the types of data stored
• CPUs are made up of billions of micro-transistors, where a single transistor represents 1 bit of information
• Data storage


  The way data is stored on a computer
• Boolean


  A data type that can only be TRUE or FALSE
• Float


  A number with a decimal value, requires multiple bytes of data to represent
• String


  Several characters, letters, or numbers, surrounded by quotation marks
• Char


  • '!'
  • True/False
  • 'Hello World!'
• Primitive data types

  • Boolean
  • Integer
  • Float
  • Char
• Additional data types

  • String
• Data types for each item

  • '1' - Char
  • FALSE - Boolean
  • 'Perhaps' - String
  • 85 - Integer
  • 75,299 - Float
  • '43,0' - String
  • 'True' - String
  • 'a' - Char
  • 0.851 - Float
  • 4951327 - Integer
• Primitive data types for each item

  • The average of marks - Float
  • Do you like chocolates? - Boolean
  • Millilitres of milk - Integer
  • Cell phone number - String
  • Price of oil per litre - Float
  • Name of pet dog - String
  • Number of eggs - Integer
• ASCII (American Standard Code for Information Interchange) uses 8 bits to encode each character
• Unicode was created to unify all encoding schemes
• UTF-8 (Unicode Transformation 8-bits) is a format to represent a value as a character
• Database


  A collection of organised data that can be accessed electronically and is designed for rapid search and retrieval
• File


  A single collection of data stored on a computing device
• File path


  The location where a file is saved, including the drive letter, folder, subfolder, filename, and file extension
• The file extension consists of a full stop followed by a combination of letters and numbers
• Each file has a unique file path that starts with the storage device's drive letter (C: or D: drive). After the drive letter is the name of the file's folders and subfolders. A backslash ('\') is used to separate the drive letter and the different folders and files. Finally, the file path ends with the name and extension of the file.
• Hierarchical structure


  The structure of how drives, folders, and files are organised in a Windows operating system, in the shape of an inverted tree
• Elements of the hierarchical structure


  • Disk drives (branches)
  • Folders
  • Sub-folders
  • Files (leaves)
• The highest level of the tree structure of a drive is the root directory, usually named the C: drive.
• Reasons for having a file structure

  • Increases efficiency when retrieving files and data
  • Guarantees high levels of productivity
  • Helps user to organise data
  • Helps user to easily identify files
  • Ensures that related data are organised and grouped together
• Guidelines for good file naming conventions

  • Keep file names short but meaningful
  • Include useful information such as the name of the project or document you are working on
  • Include the version number (e.g. V1 or -v1) and the date if there is more than one version
  • Dates should always be in the format yyyy-mm-dd so that the files will be organised in date order
• CSV file


  A file that contains text, where each line represents one row of data and the data from different columns are separated using commas
• HTML file


  A file that contains text, text references to other external files like images, and references to other files like video, CSS, or JS files
• Text files


  • Used to store plain text without formatting