Lucifer is a Latin word, which means to carry a light, or as a name it means bearer of light. It wasn't until the late medieval era that early Christians began using the term to refer to Satan, the most famous fallen angel. In ancient Rome, the term Lucifer was used by Roman astrologers to define the Morning Star, which is why you will still to this day hear Lucifer referred to as the Morning Star. The actual star being referred to in this case wasn't even a star at all, but the planet Venus, which is visible above the horizon before sunrise. The Latin roots of the word itself were most likely a literal translation of the Greek word Eosphoros, which means carrying the light, or carrying the dawn. In the Christian nomenclature system, the name Lucifer probably appeared first in the Latin translation of the Bibles of the 4th and 5th centuries. Many people think the name is rooted in Hebrew or ancient Aramaic, but obviously this is not the case at all.
According to Christianity Lucifer is the person behind evil itself, in fact he was the creator of all evil. In the Bible it says that Lucifer was the highest ranking angel in heaven before his fall. In heaven he was called the son of the dawn, or him who brings light. He was a great archangel, and prince amongst his angelic brethren. According to some Christian scholars, Lucifer was respected by most of the heavenly angels due to his rank, but that his high ranking is the reason why he began to challenge God, and eventually hate him. It was here that the first feelings of dissatisfaction within our universe emerged, as Lucifer began to slowly fall from God's grace. Lucifer would eventually be consumed with rage, envy, pride, and pure jealousy, and through these emotions he would lead a rebellion against God. His intention through this rebellion was to somehow elevate himself well above God, and eventually reign supreme over all that is and ever was.
After Lucifer openly rebelled against God with his legions, the war in heaven broke out. Michael the archangel was commanded by God to put down the rebellion, and he eventually went on to defeat Lucifer, and then cast him and all of his followers out of heaven forever. Lucifer and his demons fell to the earth, having had their wings singed off in the war with Michael. Thus they would be trapped on earth, destined to roam amongst mankind until the final battle takes place. This final battle is detailed in the Book of Revelation, where it is said that Lucifer will be defeated once and for all. In these references, it names Lucifer or Satan as the great dragon and the original deceiver who tricked Eve into sinning in the Garden of Eden. This is the only place in both the New and Old Testament where the direct connection is made between Lucifer and the serpent. For this specific serpent reference, please refer to the Book of Genesis.
There is an old legend that at the time of the earth's creation, Lucifer fell in love with some beautiful woman. According to this legend, he absolutely burned with desire for her. There was just one slight problem, Lucifer being confined to a bottomless pit, was not allowed to leave it in order to romance this fine lady. So Lucifer sent some of his demons to plead with God to let Lucifer out of the pit, so that he could be with this woman. God initially said no to these demands, but the demons persisted in begging God for mercy on their master. God finally agreed to let Lucifer out of the pit, but shortly after he arrived on earth, the woman he loved died. The legend then says that in order to teach Lucifer a lesson, God allows him to wander the earth every hundred years in torment for his lost love. The original source of this legend is completely unknown, and from the research I have done there appears to be no scriptural backing for it whatsoever.