1) The world's first credit card was introduced in 1950 by Diners Club.

2) The word "flower" contains two vowels: O and E.

3) The development of blockchain technology, first introduced in 2008 with the creation of Bitcoin, has enabled secure and decentralized digital transactions and led to the emergence of cryptocurrencies.

4) The sitcom "Friends" is known for its iconic Central Perk coffee shop, where the main characters often gather.