Spiderette is a single deck version of Spider Solitaire. It has fewer columns, and the columns begin the game with less cards in them, but other than that the rules are pretty much the same. It's an easier game to play if you don't have all the cards or the space needed to play a full game of Spider Solitaire.
Deal 21 cards into 3 columns with all but the last card placed in each column turned face down. The remaining 31 cards are placed in a Stock Pile.
When playing Spiderette Solitaire, you are able to move the bottom card in any column, or a Fully Packed Series of cards. As typical with games where you can only move fully packed series, you can not divide up a series and move it. All cards in a series must be moved together. The cards can be moved to a different column if they Build Down that column Without Regard to Suit. When a column has nothing in it but a fully packed series of cards from King to Ace, all the cards in that column can be removed from play to create an empty Space that can be filled with any available card. When you move a card or group of cards from a column, and the bottom card in that column is face down, you should turn the card face up.
When you have built a column of 13 cards that are in order from King to Ace, you may remove the cards in that column from play. Once you have removed all cards from play, you have won the game.