Be able to place appropriate elements in the head section of a web page including insert a page title to display in the browser, attach external stylesheets (with the correct hierarchy, using a relative file path), metatags to use the appropriate att

IGCSE ICT (0417) – Complete Revision Notes

1 Computer Systems, Input/Output, Storage & Networks

• Hardware fundamentals

  • CPU – central processing unit (control unit + ALU) executes instructions.
  • Memory:

    • RAM – volatile, temporary working storage.
    • ROM / Flash – non‑volatile, stores firmware and boot instructions.

  • Motherboard – houses the bus system (data, address, control) and connects all components.
  • Power supply – converts mains AC to low‑voltage DC for the computer.

• Input devices – keyboard, mouse, scanner, microphone, touch screen, digital camera, graphics tablet.
• Output devices – monitor (LCD/LED), printer (laser/ink‑jet), speakers, plotter, projector.
• Storage media

  Media	Type	Typical capacity	Typical use
  Hard‑disk (HDD/SSD)	Magnetic / solid‑state	256 MB – several TB	Primary computer storage
  USB flash drive	Flash	4 GB – 128 GB	Portable data transfer
  CD / DVD	Optical	700 MB / 4.7 GB	Backup, software distribution
  Cloud storage	Remote server	Unlimited (pay‑as‑you‑go)	Online backup, collaboration

• Network basics

  • Four main network types:

    • LAN – local area network (e.g., school or office).
    • WLAN – wireless LAN (Wi‑Fi).
    • WAN – wide area network (connects LANs over long distances).
    • Internet – global WAN providing worldwide services.

  • Key hardware:

    • Router – forwards packets between different networks; often provides NAT and DHCP.
    • Switch – connects multiple devices within a LAN, forwards frames based on MAC addresses.
    • Hub – simple repeater, broadcasts to all ports (rarely used now).
    • Bridge – connects two LAN segments, filters traffic.
    • Network Interface Card (NIC) – provides a physical connection (wired or wireless) to a network.
    • Modem – converts digital data to analogue for transmission over telephone lines or cable.

  • Wireless technologies:

    • Wi‑Fi (IEEE 802.11) – most common WLAN.
    • Bluetooth – short‑range device‑to‑device communication.
    • Infra‑red – line‑of‑sight, low‑speed links (e.g., remote controls).

  • Common protocols:

    • TCP/IP – suite that underpins the Internet.
    • HTTP / HTTPS – web page transfer.
    • FTP – file transfer.
    • SMTP – e‑mail sending.
    • POP3 / IMAP – e‑mail retrieval.

  • Emerging concepts (required for 1.5):

    • Cloud computing – delivery of services (storage, processing) over the Internet.
    • Internet of Things (IoT) – everyday objects connected to the network.
    • Artificial Intelligence (AI) – systems that learn and make decisions (e.g., voice assistants).
    • Extended Reality (XR) – VR/AR applications using networked data.

• Effects of IT on society – productivity, communication, globalisation, environmental impact, digital divide.

2 ICT Applications

3 Systems Life‑Cycle (SLC)

1. Analysis

   • Identify the problem or opportunity.
   • Gather user requirements (questionnaires, interviews).
   • Produce a feasibility report (technical, economic, legal, operational).

2. Design

   • Data‑flow diagram (DFD) to show information movement.
   • Pseudo‑code or flowchart for algorithms.
   • UI mock‑up (paper prototype or digital wire‑frame).
   • Database schema (tables, fields, primary/foreign keys).

3. Development & Testing

   • Write the program or assemble the system.
   • Create a test plan covering unit, integration, system and user‑acceptance testing.
   • Record test results and fix defects.

4. Implementation

   • Installation of hardware/software.
   • Data migration and conversion.
   • Training for end‑users.
   • Implementation strategies:

     • Direct change‑over
     • Parallel running
     • Pilot (limited area)
     • Phased rollout

5. Evaluation

   • Compare actual performance with original objectives.
   • Evaluation criteria – efficiency, effectiveness, ease of use, reliability, appropriateness.
   • Produce a post‑implementation review (technical documentation + user documentation).

4 Safety & e‑Safety

• Physical safety

  • Avoid exposed cables and trip hazards.
  • Keep liquids away from equipment.
  • Use surge protectors and UPS where required.

• e‑Safety – personal security

  • Strong passwords: at least 8 characters, mix of upper‑/lower‑case letters, numbers, symbols.
  • Two‑factor authentication where possible.
  • Phishing, pharming, smishing, vishing – recognise suspicious e‑mail, SMS, voice calls.
  • Antivirus / anti‑malware kept up‑to‑date; regular scans.
  • Secure Wi‑Fi (WPA2/3) and use VPN on public networks.

• Data protection & legislation

  • Personal data – any information that can identify an individual.
  • Sensitive data – health, financial, biometric details.
  • Legal requirements (e.g., GDPR, Data Protection Act):

    • Collect only what is needed.
    • Store securely (encryption, access controls).
    • Retain for a limited period.
    • Obtain consent and provide the right to access/correct data.

• Security threats (full syllabus list)

  • Malware – viruses, worms, trojans, ransomware.
  • Hacking – unauthorised access, password cracking.
  • Card fraud – unauthorised use of credit/debit card details.
  • Social engineering – manipulation to obtain confidential info.
  • Denial‑of‑service (DoS) attacks.
  • Physical theft of devices containing data.

• Copyright & licensing

  • Only use licensed or free‑to‑use resources.
  • Give proper attribution (author, source, licence).

5 Audience Analysis & Communication

• Identify purpose, needs, prior knowledge and accessibility requirements of the target audience.
• Choose appropriate media (text, images, audio, video) and tone (formal, informal).
• Communication sub‑topic – Email & Netiquette

  • Clear subject line.
  • Use appropriate salutations and sign‑off.
  • CC for secondary recipients; BCC for privacy.
  • Attach files using sensible naming conventions.
  • Avoid ALL CAPS (shouting) and excessive punctuation.
  • Proof‑read for spelling, grammar and tone.
  • Spam awareness – recognise unsolicited bulk mail.

6 File Management, Images & Layout

• File naming conventions

  • No spaces – use underscores or hyphens.
  • Include version number (e.g., report_v2.docx).
  • Use lower‑case extensions.

• Common file formats

  Type	Extension(s)	Typical use
  Document	.doc, .docx, .pdf	Reports, essays, printable documents
  Spreadsheet	.xls, .xlsx, .csv	Data analysis, budgets, charts
  Presentation	.ppt, .pptx	Slideshows, project briefings
  Image	.jpg/.jpeg, .png, .gif, .svg	Photos, graphics, icons, vector art
  Web page	.html, .htm	Website authoring

• Image editing basics

  1. Open in an editor (Paint, GIMP, Photoshop).
  2. Resize – maintain aspect ratio; consider web‑friendly dimensions.
  3. Crop – remove unwanted areas.
  4. Adjust colour, contrast, brightness if needed.
  5. Save in appropriate web format:

     • JPEG – photographs (lossy compression).
     • PNG – graphics with transparency or text.
     • SVG – scalable vector graphics.

• Page layout & structure (HTML basics)

  • Headings: <h1>–<h6> for logical hierarchy.
  • Paragraphs: <p> for body text.
  • Lists: <ul> (bulleted) and <ol> (numbered).
  • Tables: <table> with <thead>, <tbody>, <tr>, <th>, <td>.
  • CSS – external style sheets control colours, fonts, margins, layout.

7 Document Production, Databases & Presentations

• Word processing

  • Use styles for headings, body text, and captions.
  • Headers/footers for page numbers, document title, author.
  • Automatic table of contents (TOC) generated from heading styles.
  • Mail merge – combine a template with a data source (e.g., letters to parents).

• Spreadsheets

  • Formulas – arithmetic, logical, text manipulation.
  • Functions – SUM, AVERAGE, MAX, MIN, IF, VLOOKUP, COUNTIF, DATE, etc.
  • Data validation – restrict entries (drop‑down lists, numeric limits).
  • Pivot tables – summarise large data sets.
  • Charts – column, line, pie, scatter; choose type based on data relationship.

• Databases

  • Key concepts: table, field, record, primary key, foreign key.
  • Simple SQL‑like queries:

    SELECT * FROM Students WHERE Grade = 'A' ORDER BY Surname;

  • Forms – for data entry (e.g., student registration).
  • Reports – formatted output (e.g., sales summary).
  • Documentation:

    • Technical documentation – data dictionary, schema diagrams.
    • User documentation – how‑to guides, help screens.

• Presentations

  • Slide master – ensures consistent layout, fonts, colours.
  • Use multimedia sparingly (audio, video) to support key points.
  • Presenter notes – cue cards for the speaker.
  • Accessibility – readable fonts, sufficient contrast, alt‑text for images.

8 Spreadsheets – Core Skills

• Cell referencing

  • Relative – A1 (changes when copied).
  • Absolute – \$A\$1 (fixed column and row).
  • Mixed – \$A1 (fixed column) or A\$1 (fixed row).

• Essential functions (syntax examples)

  =SUM(A1:A10)                // total of a range
  =AVERAGE(B2:B15)            // mean value
  =MAX(C1:C20)                // highest value
  =MIN(D5:D12)                // lowest value
  =IF(E2>100,"High","Low")    // logical test
  =VLOOKUP(F2,\$A\$1:\$C\$20,3,FALSE) // lookup value in first column
  =COUNTIF(G:G,"Yes")         // count cells meeting criteria
  =TEXT(H2,"DD/MM/YYYY")      // format date as text
  

• Conditional formatting – e.g., highlight cells >0 in green, <0 in red.
• Chart selection guide

  Data type	Best chart
  Comparisons of categories	Column or bar chart
  Trends over time	Line chart
  Proportions of a whole	Pie chart
  Relationships between two variables	Scatter plot

9 Website Authoring – The <head> Section

9.1 Why the <head> Matters

• Contains metadata that browsers, search engines and assistive technologies use before rendering the page.
• Controls character encoding, page title, external resources (CSS, favicons), viewport for mobile devices, and default link behaviour.

9.2 Essential Elements (recommended order)

1. Character set declaration

   <meta charset="UTF-8">

   Ensures all characters display correctly.

2. Page title

   <title>Concise, relevant page title</title>

   Appears on the browser tab and in search results.

3. External stylesheet links (relative paths)

   <link rel="stylesheet" href="css/reset.css">
   <link rel="stylesheet" href="css/layout.css">
   <link rel="stylesheet" href="css/theme.css">
   

   Later sheets override earlier rules – this hierarchy is crucial.

4. Meta‑tags for SEO and device handling

   <meta name="description" content="Brief, keyword‑rich summary of the page (150‑160 characters)">
   <meta name="keywords"    content="ICT, IGCSE, HTML, head section, meta tags">
   <meta name="author"      content="Student Name">
   <meta name="viewport"    content="width=device-width, initial-scale=1.0">
   

5. Base element (optional) – sets default target for all hyperlinks.

   <base target="_self">