YYMMDD is the best date format

I have tried every way of writing dates for files, notes, and folders. The best I have found is YYMMDD.

Why it wins

• Alphabetising equals chronology: 180915, 181001, 181201 will sort in the correct order in any file browser, search result, or text list.
• Compact, fixed width: Six digits are quick to type, easy to scan, and align neatly.
• Locale neutral: Avoids DD/MM/YY vs MM/DD/YY confusion.
• Great for prefixes: Put the date at the start, then a hyphen, then your title. Your lists stay clean and chronological.

When to use YYYYMMDD

If the century could be ambiguous (legal docs, historical records, or anything that might outlive you), use YYYYMMDD.

• Example (short‑lived notes, clear context): 180915-trip-ideas.md
• Example (long‑lived, century matters): 20180915-contract-signed.pdf

Alternatives are worse

• DD/MM/YY or MM-DD-YY - Ambiguous, inconsistent in standards, and they sort incorrectly.
• MM-DD-YY is also non chronological.
• Month names - Human-friendly, but hard to scan and sort (15 Sep 2018 vs Sep 15, 2018).

Simple rule

Start every filename with YYMMDD-. If the century matters, upgrade to YYYYMMDD-. That is it.