its central themes and the relationships of thecharacters to one another. Its literal presence in the play is Troy and Cory’s long-standing construction of a fence for their home. Figuratively, however, it refers to the many types of intangible barriers that surround Troy and his loved ones—the emotional barrier between Troy and Cory, between Troy and Rose, and the racial and socio-economic barriers that have hounded Troy all his life.

In act 2, scene 1, fences are described as barriers that serve to either keep something out or keep something in. Tony believes in the former while Rose believes in the latter—thus, the construction of a fence for their home serves to emphasize the contrast between their personal values. It is also in this way that their eventual split is foreshadowed.

The resolution of the play comes in the character of Troy’s brother, Gabriel, who is named after the archangel. At Troy’s funeral, Gabriel arrives to blow his trumpet and open the gates of St. Peter for his brother. When his trumpet refuses to sound, he performs a ritualistic dance that opens the gates of heaven. Thus, the play is concluded with the dissolution of the barriers which were a source of pain and frustration for Tony all his life—in his death, the “fences” were finally opened.

To add to the previous answer for this question, there is a really poignant scene in the play that points directly to the importance of the title. In Act Two, Scene One, the story is well established as a conflict between Troy and his inner demons as well as a conflict between Troy and his family members. Cory, his son, and Rose, his wife, have different expectations of him than he has of himself, and vice versa. This scene in Act Two reveals some of those misunderstood expectations, and it reveals how the fence stands as a symbol for the type of love and relationships the family members value, particularly Rose, who asked Troy and Cory to build the fence.

In this scene, Bono, Troy's friend from work, is visiting as he usually does, and Cory is helping Troy cut the wood for the fence. Cory comments that he doesn't understand why his mother wants a fence built anyway, and Troy agrees that he doesn't understand, since they don't own many valuable things that people would want to steal. To this, Bono responds:

"Some people build fences to keep people out...and other people build fences to keep people in. Rose wants to hold on to you all. She loves you."

Rose's role in the family is the role of peacemaker and caretaker, so this idea of the fence symbolizing an embrace, a surrounding mother's arms, is relevant to her character. Ultimately, the fact that the fence takes so long to build and is unfinished for most of the play contributes to the idea that Troy and Cory will not be kept. Troy will cheat and die before long, and Cory will join the military and move away. The fence, which was meant to pull everyone together, will serve more as a catalyst for their parting and as a shell for Rose and baby Raynell to retreat into once they are left alone.

The significance of a fence in this play is that it serves a dual purpose -it keeps people in and it also keeps them out, both literally and figuratively.

The most obvious fence is the literal fence that is being built throughout the play. A physical fence implies ownership (and this play can be viewed as the African American version of the American Dream theme of home ownership). Building a fence around your home is a way to claim it as yours by determining who can and cannot leave.

For Troy, there is a figurative fence that keeps him stifled at work. He asks the question of why the blacks are always lifting the trash while the whites are driving the trucks. He sees this as a fence created by the white majority to keep the black minority in their place socio-economically.

Another fence is the fence that kept Troy in place during his time in prison. In this case, the walls kept him inside. When he builds a fence around his own home, he is able to keep his family inside (not literally, but it acts as a barrier between his family and the dangers of the world around him).

Finally, the characters build fences between each other. Troy and Rose have a fence between them from the standpoint of gender difference. Troy cannot express to Rose the same emotions he can express to Alberta. This is one example of fences built between people. Another lies in the Troy and Cory dichotomy. Troy tries to fence Cory in by keeping him from pursuing his dreams because he believes that Cory will fail and wants to protect him from that.

Each character has a fence of some sort that he or she has created either to keep others out or to lock himself or herself inside. Gabriel is the only exception. The simplicity of his beliefs, while flawed from the perspective of "normal" society, actually allow him to transcend self and societally imposed fences.

The fence is given a specific significance in the dialogue of the play when it is referred to as something that keeps things out and also keeps things in. Regarding Troy and his family, the fence carries this meaning and more. 

Troy's character, in particular, has a set of symbolic relations to the fence.  As a baseball player, Troy's specialty was hitting home runs - hitting the ball over the fence. This fact has bearing on Troy's character and is mentioned with explicit reference to the idea that Troy was no pleased unless he hit the ball all the way over the fence.

Also, Troy feels that he was kept out of major league baseball because of the color of his skin. He was kept on the wrong side of metaphorical fence.

Most significantly, Troy's character relates to fences in an emotional sense.  

Unable to open up to those that he loves, Troy keeps much of his emotion inside, building imaginary fences between himself and his family and friends.

For fifteen years of his life, Troy was in prison, kept inside the fences there. Outside of prison, he feels that his life continues to be delineated and limited by various forces and factors and he attempts to exceed these limitations. 

We see this in his insistence that his companies policy change regarding who can and who cannot drive the trucks. We see it in his continued bitterness regarding his athletic career. We see this also in his adultery. 

Finally, we see Troy's desire to escape or exceed his limitations in his fixation on death and his sense that he has a chance to defeat this natural and inevitable opponent. Death is the fence that limits Troy in a way that is both actual and symbolic. He repeatedly challenges death and recounts stories of his encounters with death. 

At the end of his life, after ruining his marriage, losing his one friend and destroying his relationship with Cory, death is the only figure left inside the fence with Troy. 

Troy finally succeeds in isolating himself from his wife, his brother, his sons, and his friend.

Having build up barriers between himself and his family, Troy is alone with his opponent. He dies, challenging death, taking a swing with his baseball bat in an effort to hit one more over the fence. 

There is an interesting part of August Wilson's description of the setting in which his play Fences takes place:

Fences are significant of many things in this play. In fact, fences means different things for different people. For example, Rose believes the incomplete fence surrounding the home will maintain her family safe inside it. However, Troy believes the fence keeps people out . After the death of Alberta, Troy finishes building the fence as a way of keeping Death, a character in the play, from claiming anyone else.

Fences meant something else for Troy as well. He constructs a fence surrounding his son Cory in order to keep him from his football dreams, thus creating an invisible "fence" in their relationship.

To start answering this question, think about the way fences function as symbols in this play. First, why do different members of Troy's family want to build a fence? As Bono says in Act II, "Some people build fences to keep people out...and other people build fences to keep people in. Rose wants to hold on to you all." Rose, Troy's wife, wants to build a fence to keep her family safe and protected, much as she sees Jesus as a fence and protector. Troy, on the other hand, wants to build a fence to keep death out after Alberta, the mother of his baby, dies in childbirth. 

As much as fences can offer protection, fences can also keep people out. Think about the larger meaning of fences in Troy's life. He has been kept out of playing baseball in the white leagues because he is African-American. He won't let his son, Cory, play football because he is afraid of racism, and, as a result, Cory decides to leave home. The fences, or ways that Troy has been left out of parts of American life because of racism, cause there to be fences, or divisions, in his own family. In considering the answer to this question, think about the ways in which fences keep people in but also keep people out.