Sunday was a very special occasion - the date is a palindrome, meaning it is the same when read forwards and backwards.

It is February 2, 2020, or 02/02/2020, in both the MM/DD/YYYY format and the DD/MM/YYYY format. At just after 2 am, it was 02:02:20 on 02/02/2020. This is the only time such a date will occur this century, reported CNN.

The previous palindrome date came 909 years ago on 11/11/1111. The next will come in 101 years on 12/12/2121 and after that there will not be another until 03/03/3030. Solihull School Maths Department wrote on Twitter: "Today is a Palindrome Day in all date formats (UK, USA, ISO). It's also a palindrome day of the year (33) and there are a palindrome number of days left in the year (333). Quite a unique day!"

The Royal Wedding Chapel in Las Vegas was advertising weddings on the "significant" date, pointing out that your two-year anniversary would fall on 2-2-22. "Two being the ultimate symbolic number representing you and your spouse to be."

November 11, 2011 caused a major stir. When the clock struck 11:11:11 on 11/11/11. It was the only double-figure palindromic date and will not come round again for 100 years, in 2111.

However, it is not as perfect as 02/02/2020, because using the full year, 2011, ruins the symmetry.

Las Vegas chapels were bursting at the seams with couples wanting to tie the knot on 11/11/11, with "queen of nightlife" Tiffany Masters holding what she billed as the world's largest reception.

Verizon Wireless launched its Droid Razr at 11:11 on 11/11/11 and there was even a movie "11-11-11," about an American author plagued by strange happenings and constant sightings of the number 11.

Human brains are naturally inclined to look for patterns, and many consider such dates lucky. Daniel Hardt, president of Life Path Numerology Center in Indianapolis, called it a "powerful day."

In September, there was a week of palindrome dates using the US format, if you removed the 20- in the year. There was 9-10-19, 9-11-19 and so on, through to 9/19/19. But of course, these only worked with the US format of MM/DD/YYY.

There had been one of these every year since 2011, but that was the last of the century.

A palindrome is any word, phrase or sequence of numbers that reads the same whether you read it forward or backward, such as "mom," "race car" or "tacocat." Author James Joyce invented "tattarrattat," which is supposed to be the sound of a knock on the door and the longest single-word palindrome in the Oxford English Dictionary.

Famous palindromes include "rats live on no evil star," "never odd or even" and "a man, a plan, a canal, Panama." The phrase "A toyota's a toyota" can continue as a palindrome forever, as in "A toyota's a toyota's a toyota..."

Palindrome comes from the Greek words "palin," which means "again, back" and "dromos," meaning "running," according to Dictionary.com. So palindrome is a word of phrase that runs back on itself.