Index cards are small, rectangular pieces of card stock, typically measuring 3 by 5 inches or 4 by 6 inches. They are commonly used for organizing information, taking notes, or creating flashcards. People often use them in educational settings, for study aids, or to jot down quick ideas and reminders. These cards can be easily written on, allowing for both handwritten and printed text. They are often stored in boxes or files for easy access and can be color-coded for better organization. Index cards are a versatile tool for students, teachers, and anyone needing to manage information efficiently.