The Paschal candle is a large, white candle used at liturgy in the Western Rites of Christianity (Roman Catholic, Anglican, Lutheran, etc.). A new Paschal candle is blessed and lit every year at Easter, and is used throughout the Paschal season which is during Easter and then throughout the year on special occasions, such as baptisms and funerals.
The Paschal candle is the first candle to be lit with a flame from this sacred fire, representing the light of Christ coming into the world. This represents the risen Christ, as a symbol of light (life) dispelling darkness (death). As it is lit, the minister may say words similar to: "The light of Christ, rising in Glory, dispel the darkness of our hearts and minds."
The flame of the Paschal candle symbolizes the eternal presence of Christ, light of the world in the midst of his people; he who is the Second Person of the Trinity, the Alpha and Omega. The Paschal candle is sometimes referred to as the "Easter candle" or the "Christ candle." The term "Paschal" comes from the word Pesach, which in Hebrew means Passover, and relates to the Paschal mystery of salvation.

The equivalent of the Paschal candle in the Western Orthodox Church is the Paschal trikirion which differs both in style and usage.

For congregations that use a Paschal candle it is the largest candle in the worship space. In most cases today the candle will display several common symbols:

1.The cross is always the central symbol, most clearly identifying it as the Paschal candle
2.The Greek letters alpha and omega signify that God is the beginning and the end (from the Book of Revelation)
3.The current year represents God in the present amidst the congregation
4.Five grains of incense (most often red) are embedded in the candle (sometimes encased in wax "nails" during the Easter Vigil to represent the five wounds of Jesus: the three nails that pierced his hands and feet, the spear thrust into his side, and the thorns that crowned his head.
In the mediaeval church Paschal candles often reached a stupendous size. The Paschal candle of Salisbury Cathedral was said to have been 36 feet tall. Today, in the United States and Southern Europe (e.g., Italy and France) the candle is approximately 2 inches in diameter and 36 to 48 inches tall; in Northern Europe the candle tends to be shorter in height (19 to 24 inches) and wider in diameter (3 to 5 inches).
Source : http://www.candlecarving.info/