The nurse's role in Shakespeare's Romeo and Juliet is primarily as comic relief but she serves also as a confidante and mediator to Juliet. Her personality is used to contrast other characters including Juliet and Lady Capulet.
The Nurse has been with the Capulet family since Juliet was a baby and has taken care of Juliet her entire life. Her knowledge of the family gives the reader information, such as Juliet's age. Because of their extensive past the nurse and Juliet have a close bond filled with trust. Juliet is able to tell the nurse about Romeo and her plans to marry him. The nurse helps arrange the marriage between Romeo and Juliet.
The nurse acts as a messenger to Romeo and Juliet. The first time the reader sees this is at the ball when the nurse tells Romeo and Juliet of the other's identity. Other times she does this is when they are arranging the marriage and after Tybalt's death.
This sometimes causes conflict, which moves the play along. Delivering the news that Romeo has killed Tybalt hurts Juliet very much and makes her emotional. The nurse tells Juliet to forget Romeo and to marry Paris, which makes Juliet angry and makes her lose confidence in the nurse. Losing her confidence in the nurse causes Juliet to seek other help and motivates her to seek action, causing her eventual suicide.
The nurse's contrasting personality is also important. She is vulgar and humorous compared to Lady Capulet is who is more reserved and serious. She is always willing to share her opinion and when telling it, she is honest. Her constant talking and joking brings a light heartedness over the play's generally tragic themes. She contrasts Juliet's views of love. The nurse's idea of love is more sexual than the innocent Juliet's. The nurse wants Juliet to find a good-looking suitable partner but Juliet is looking for intense love. Although they have differences in opinion, the nurse truly wants what is best for Juliet.
The nurse is more than comic relief; she is a trusted confidante to Juliet and moves the action of the play along. She is also important in the contrast of characters to bring out certain qualities in Juliet and her mother, Lady Capulet.