The term "tarot spread" (also called a layout) refers to a specific pattern in which the tarot cards are placed during a reading. These can be as simple as a one card spread to spreads that use multiple cards.
Most spreads have many different variations you can use depending on the need. For example, the cards of a simple three card spread can be designated as "past, present, future," or "obstacle, advice, outcome."
A commonly used spread is the Celtic Cross, which uses ten cards. Even though the Celtic Cross is somewhat standardized, variations do exist. The pattern of the Celtic Cross spread is set. That is, the actual configuration of the cards doesn't change from one Celtic Cross spread to another. What changes is the order in which the cards are laid down. There is no one "right" way to do a Celtic spread, just different ways. We especially love the revamped version of the Celtic Cross created by Kate, the Daily Tarot Girl!