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1. What is Data?

Data is any collection of facts, values, or measurements that can be recorded, stored, and processed by computers or humans.

• Simple examples: Numbers (42), words (“hello”), dates (2025-08-06), true/false (yes/no), files, images, videos, etc.
• In technology: Data is the raw material for software, analytics, machine learning, business intelligence, etc.

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2. Types of Data

Data can be classified in several ways. The most common are:

A. By Structure

Type	Description	Example
Structured	Organized in fixed fields/columns, like a table	Databases, Excel spreadsheets
Semi-Structured	Has some organization but not a strict schema	JSON, XML, CSV, log files
Unstructured	No pre-defined format or schema	Images, videos, emails, PDFs

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B. By Nature/Content

Type	Description	Example
Numeric	Numbers, integers, decimals	100, 3.14, -7
Textual	Words, sentences, text blocks	“Customer name”, “Review: great product”
Categorical	Labels or categories	Red/Green/Blue, Male/Female
Boolean	True/False, Yes/No, 0/1	true, false, 1, 0
Date/Time	Dates, timestamps	2025-08-06, 12:30 PM
Spatial	Locations, coordinates	GPS points, maps
Multimedia	Images, audio, video, graphics	profile_pic.jpg, song.mp3, video.mp4

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C. By How It Arrives

Type	Description	Example
Batch	Collected and processed in chunks	Daily sales report, nightly backups
Streaming	Arrives and processed in real-time	Website clicks, sensor data, live chat

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3. Sources of Data

Data can come from almost anywhere. Here are typical sources in tech and business:

Source	Description	Example
Transactional	Systems that record daily business	Sales databases, banking systems
Operational	Logs/events from running systems	Web server logs, app logs, error logs
External APIs	Data from third-party services	Weather APIs, social media APIs, payment APIs
Manual Entry	Human input	Online forms, surveys, spreadsheets
IoT/Sensors	Physical devices measuring things	Thermometers, cameras, GPS trackers
Files/Blobs	Uploaded or shared files	CSVs, Excel, PDFs, videos
Web Scraping	Data extracted from websites	Product prices, news headlines
Public Data Sets	Open government or community data	Census data, COVID-19 stats, Wikipedia dumps
Streaming Services	Live feeds, events	Kafka, Kinesis, Event Hubs

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Summary Table

Type	Examples
Structured	SQL databases, Excel tables
Semi-Structured	JSON, XML, CSV
Unstructured	Images, emails, audio, PDFs
Numeric	1, 2.5, -99
Textual	“Hello”, “Feedback”
Categorical	“Red”, “Male”, “Success”
Boolean	true/false, 0/1
Date/Time	2024-05-23, 17:45
Batch	Daily ETL jobs
Streaming	Real-time clickstream, IoT
Sources	Databases, APIs, Logs, Sensors, Files, Scraping

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