ICDL Computer & Online Essentials (ICDL) cheat sheet

Hardware is the physical equipment (CPU, RAM, storage, monitor); software is the set of instructions (OS, applications) that runs on it.

RAM is volatile working memory cleared at power-off; storage (HDD/SSD) is non-volatile and retains files when the machine is off.

File extensions map to file types: .docx (word processing), .xlsx (spreadsheet), .pptx (presentation), .pdf (fixed-layout document), .jpg/.png (images), .mp3 (audio), .mp4 (video).

A folder (directory) is a container for files; a path such as C:\Users\Name\Docs.txt names the drive, folders and file in order.

Copy duplicates a file leaving the original; cut removes it to the clipboard; paste places clipboard content at the destination; delete sends to Recycle Bin (recoverable) while Shift+Delete or emptying the bin is permanent.

Common shortcuts: Ctrl+C copy, Ctrl+X cut, Ctrl+V paste, Ctrl+Z undo, Ctrl+A select all, Ctrl+S save, Ctrl+P print, Ctrl+F find.

File size units scale by 1024: 1 KB = 1024 bytes, 1 MB = 1024 KB, 1 GB = 1024 MB, 1 TB = 1024 GB.

Operating system functions include managing hardware and memory, running applications, handling input/output, and enforcing user accounts and permissions.

Backup keeps a second copy on separate media; a strong password mixes upper and lower case, digits and symbols and is not a dictionary word.

A URL has the form scheme://host/path: the scheme (http, https) defines the protocol, the host is the domain name, and the path locates the resource.

HTTPS encrypts traffic with TLS; the padlock and https indicate an encrypted connection, not that the site content is trustworthy.

A browser stores visited addresses in history, saved sites in bookmarks/favorites, and downloaded files in a downloads folder; clearing history does not delete bookmarks.

Search operators refine results: quotation marks match an exact phrase, a minus sign excludes a term, and site: restricts results to one domain.

Email fields: To is the primary recipient, Cc is a visible copy, Bcc is a hidden copy, Subject summarizes the message, and attachments are separate files sent with it.

Reply sends to the sender only; Reply All sends to the sender plus all other recipients; Forward resends the message to new recipients.

Phishing is a fraudulent message that impersonates a trusted party to steal credentials; signs include urgent demands, mismatched sender addresses and unexpected links.

Cookies are small data files a site stores in the browser to remember state such as login sessions or preferences; they are not programs and do not execute.

Cloud storage keeps files on remote servers accessible from any device with an account; sharing permissions (view vs edit) control what recipients can do.