What does a file extension (like .jpg or .mp4) tell the operating system?

Which program should open the file and what format the data inside uses How large the file is and when it was created Who owns the file and whether it is encrypted Where the file is stored on the hard drive

You receive a suspicious email with an attachment called 'invoice.pdf.exe'. What should concern you about this filename?

The real extension is .exe (an executable program) disguised to look like a harmless PDF PDF files can't be emailed so this is automatically suspicious Files with two dots in the name are always corrupted Invoice files should always be .docx, never .pdf

What is a database, and why do large websites use them instead of just storing data in files?

A database is organized storage that allows fast searching, filtering, and updating of large amounts of structured data A database is just a large folder containing thousands of small text files Databases are required by law for websites with more than 1,000 users A database is a type of very fast RAM reserved for website use

Why do websites format data as JSON or XML when sending it between a server and your browser?

JSON and XML are text-based formats that both the server and browser can read and generate regardless of what programming language they use JSON and XML are encrypted formats that prevent hackers from reading web traffic They are required by internet standards for all web communication JSON and XML compress data to make it faster to transfer over slow connections

What is the 'lifecycle of digital information' — from creation to deletion?

Data is created, stored, processed, shared, archived or backed up, and eventually deleted or overwritten Data flows from RAM → hard drive → internet → cloud → RAM in a loop Digital data doesn't have a lifecycle — once created it exists forever Data is always deleted within 30 days by law in most countries

A spreadsheet, a photo, and an audio file are all 'data.' What makes them different from each other at the binary level?

The same 1s and 0s are interpreted differently based on the file format — the format defines the rules for reading the binary data Photos use a different type of electricity than audio files Only text and photos are stored as binary; audio uses a separate analog system Different data types are stored in physically separate sections of the hard drive

You take 100 photos on a hiking trip and copy them to a USB drive. Later the USB drive is damaged and some files are corrupted. What does 'file corruption' mean?

Some of the bits in the file were changed or lost, so the file format data no longer makes sense to the program trying to read it The file was accidentally encrypted by the damage The file was split into pieces and stored on different drives The filename was changed so the OS can no longer find the file

Why is the 3-2-1 backup rule recommended for important data?

3 copies, on 2 different media types, with 1 copy off-site — this protects against most failure scenarios including fire, theft, and hardware failure Back up 3 times per day, 2 days per week, 1 day per month 3 external drives, 2 cloud services, 1 USB drive 3 GB per backup, 2 backups per week, 1 year of retention

What does it mean when a photo is '12 megapixels'?

The image is made up of 12 million individual pixels arranged in a grid The photo file is exactly 12 megabytes in size The camera can take 12 million photos before its memory is full The image uses 12 colors to represent all visible shades

If you delete a file from a cloud storage service like Google Drive, what typically happens to the data?

It moves to a trash/recycle folder and is kept for a period (often 30 days) before being permanently deleted from Google's servers It is immediately and permanently deleted from all Google servers worldwide It gets transferred to your local computer automatically before deletion It is archived in a public database accessible to anyone