How many players are required in a game of Solitaire?

Solitaire or Patience, as it is commonly called in parts of Europe, is a game that can be played with just one player, and requires only a standard deck of 52 playing cards. The objective of most solitaire games is to organize a shuffled deck of cards into four piles (one for each suit) in ascending order from Ace to King. The most well-known version of Solitaire is Klondike which is the game that most people identify with “solitaire”.

Source: Play Card Deck