What is the relevance of Ibsen's title A Doll's House?

Henrik Ibsen’s ground-breaking play A Doll’s House premiered in Copenhagen in 1879.Particularly for modern audiences, it’s easy to make the mistake of believing that Torvald Helmer does not love his wife. He patronizes, controls, and bullies her. He delights in displaying her beauty to his friends (under carefully monitored circumstances), as when he dresses her as a Neapolitan fisher-girl and has her dance at a neighbor's party. He declines to speak with her as an equal. Surely Torvald would treat Nora with more respect if he truly loved her? The key to understanding the play — and the significance of its title — is to realize that Torvald is behaving exactly as he believes a loving husband should. He is not trying to insult or demean Nora. Both Nora and Torvald are trapped in the conventions of nineteenth century Europe: a culture that assumes the moral and intellectual inferiority of women, and believes that women have no real identity except in relation to their parents, husbands, and children.During the course of the play, Nora undergoes a crisis and an epiphany, leading her to gain new perspective on her marriage and on her own humanity. She realizes that she has never truly grown up, never developed her own mind and spirit, never explored her own identity as an individual human being. Because of that, her marriage has been no true partnership. She has been playing at marriage, like a child playing with dolls in a doll’s house. This is a crime against her own children, but above all against herself.Here’s how she explains it to Torvald in the final scene of the play:NORAWe have been married now eight years.  Does it not occur to you that this is the first time we two, you and I, husband and wife, have had a serious conversation?
. . . TORVALDBut, dearest Nora, would it have been any good to you?NORA That is just it; you have never understood me.  I have been greatly wronged, Torvald, ­first by papa and then by you.. . .When I was at home with papa, he told me his opinion about everything, and so I had the same opinions; and if I differed from him I concealed the fact, because he would not have liked it.  He called me his doll-child, and he played with me just as I used to play with my dolls.  And when I came to live with you ­—TORVALDWhat sort of an expression is that to use about our marriage?NORA (undisturbed).  I mean that I was simply transferred from papa’s hands into yours.  You arranged everything according to your own taste, and so I got the same tastes as you ­or else I pretended to, I am really not quite sure which. ­I think sometimes the one and sometimes the other.  When I look back on it, it seems to me as if I had been living here like a poor woman ­just from hand to mouth.  I have existed merely to perform tricks for you, Torvald.  But you would have it so.  You and papa have committed a great sin against me.  It is your fault that I have made nothing of my life.TORVALDHow unreasonable and how ungrateful you are, Nora!  Have you not been happy here?
. . .NORA No, only merry.  And you have always been so kind to me.  But our home has been nothing but a playroom.  I have been your doll-wife, just as at home I was papa’s doll-child; and here the children have been my dolls.  I thought it great fun when you played with me, just as they thought it great fun when I played with them.  That is what our marriage has been, Torvald.
Nora must now leave her husband and children and set out alone to educate herself:  “I believe that before all else I am a reasonable human being, just as you are ­or, at all events, that I must try and become one.” The click of the door closing behind Nora is one of the most famous sound effects in the history of theater.Even today, the idea of a woman leaving her children in order to defend her own spirit is deeply controversial. When Michael Cunningham’s novel The Hours was published in 1998, many readers were shocked by the character of Laura Brown, who does exactly that. Imagine the uproar sparked all over nineteenth century Europe by Nora’s determination to leave her metaphorical doll's house and step into her own humanity.
http://www.mnc.net/norway/Ibsen.htm