Question 1

What is UUID v4?

Accepted Answer

UUID v4 is a completely random universally unique identifier defined in RFC 4122. It uses cryptographically secure random number generation, making it unpredictable and suitable for security-sensitive applications. V4 is the most popular UUID version due to its simplicity and lack of personally identifiable information.

Question 2

When should I use UUID v4?

Accepted Answer

Use UUID v4 when you need secure, random identifiers without time-based ordering. Perfect for database primary keys when chronological order isn't important, session IDs, API tokens, security tokens, and any scenario requiring unpredictable unique identifiers. V4 is ideal for privacy-focused applications.

Question 3

What's the difference between UUID v4 and v6?

Accepted Answer

UUID v4 is completely random with no inherent ordering, while UUID v6 is time-ordered and sortable. V4 is better for security-sensitive scenarios and privacy, as it contains no timestamp or MAC address. V6 is better for database performance when you need time-based sorting or chronological queries.

Question 4

Is UUID v4 secure for sensitive data?

Accepted Answer

Yes, UUID v4 is cryptographically secure and suitable for sensitive applications. It uses secure random number generation with 122 bits of randomness, making collisions extremely unlikely. V4 doesn't expose any information about when or where it was created, making it privacy-friendly and secure for tokens and identifiers.

Version	Time-based	Sortable	Best Use Case
v1			Legacy systems
v4			Random IDs, security
v6			Modern databases
v7			Latest standard (2024)

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