1 Samuel 17:1-58New American Standard Bible (NASB)
Goliath’s Challenge
17 Now the Philistines gathered their armies for battle;
Who were the Philistines?
1. The Philistines. (1.The Philistines are referred to as the descendants of the Casluchim in Genesis 10:14 and Exodus 13:17. Known as a seafaring nation, thePhilistines were a non-Semitic people who left Crete and arrived in Canaan at the beginning of the 12th century B.C.E.) God had instructed the Israelites to destroy the Philistines and completely remove them from the Promised Land and spare not one of them alive. and they were gathered at Socoh which belongs to Judah, and they camped between Socoh and Azekah, in Ephes-dammim.
Where is Socoh and why did the Philistines choose to Camp there?
Socoh (2.Socoh was in the district of Shefelah. (Joshua 15:35) (Chronicals 11:7; 8:1:8) It lay 8 to 9 Roman miles from Eleutheropolis on the road to Jerusalem. Ephes-Dammim is a significant spot militarily as it is a gate way into Juda is it commands the hills overlooking the roadway in.
The International Standard Bible Encyclopedia refers to it as
Some spot between Socoh and Azekah (1 Samuel 17:1) where the Philistines were encamped; called in 1 Chronicles 11:13, "Pas-dammin." Ephes" end of" or "boundary" and the whole word may mean the "boundary of blood." The deep red color of the newly plowed earth in this situation is noticeable and may have given origin to the idea of "blood" (compare ADUMMIM). Cheyne suggests that from 'adhummin, to dammim, is an easy step, and that the former, meaning "red brown earth," may have been the original. No other satisfactory locality has been found to explain the name or fix the site.

2 Saul and the men of Israel were gathered and camped in the valley of Elah, and drew up in battle array to encounter the Philistines.
Effectivley the two armies were each on a hilltop over looking a valley below.

3 The Philistines stood on the mountain on one side while Israel stood on the mountain on the other side, with the valley between them. 4 Then a champion came out from the armies of the Philistines named Goliath, from Gath, whose height was six [a]cubits and a span. 5 He had a bronze helmet on his head, and he was clothed with scale-armor [b]which weighed five thousand shekels of bronze. 6 He also had bronze [c]greaves on his legs and a bronze javelin slung between his shoulders. 7 The shaft of his spear was like a weaver’s beam, and the head of his spear weighed six hundred shekels of iron; his shield-carrier also walked before him. 8 He stood and shouted to the ranks of Israel and said to them, “Why do you come out to draw up in battle array? Am I not the Philistine and you servants of Saul? Choose a man for yourselves and let him come down to me. 9 If he is able to fight with me and [d]kill me, then we will become your servants; but if I prevail against him and [e]kill him, then you shall become our servants and serve us.” 10 Again the Philistine said, “I defy the ranks of Israel this day; give me a man that we may fight together.” 11 When Saul and all Israel heard these words of the Philistine, they were dismayed and greatly afraid.
12 Now David was the son of [f]the Ephrathite of Bethlehem in Judah, whose name was Jesse, and he had eight sons. And [g]Jesse was old in the days of Saul, advanced in years among men. 13 The three older sons of Jesse had[h]gone after Saul to the battle. And the names of his three sons who went to the battle were Eliab the firstborn, and the second to him Abinadab, and the third Shammah. 14 David was the youngest. Now the three oldest followed Saul,15 but David went back and forth from Saul to tend his father’s flock at Bethlehem. 16 The Philistine came [i]forward morning and evening for forty days and took his stand.
17 Then Jesse said to David his son, “Take now for your brothers an ephah of this roasted grain and these ten loaves and run to the camp to your brothers.18 Bring also these ten cuts of cheese to the commander of their thousand, and look into the welfare of your brothers, and bring back [j]news of them. 19 For Saul and they and all the men of Israel are in the valley of Elah, fighting with the Philistines.”
David Accepts the Challenge
20 So David arose early in the morning and left the flock with a keeper and tookthe supplies and went as Jesse had commanded him. And he came to the circle of the camp while the army was going out in battle array shouting the war cry.21 Israel and the Philistines drew up in battle array, army against army. 22 Then David left his baggage in the [k]care of the baggage keeper, and ran to the battle line and entered in order to greet his brothers. 23 As he was talking with them, behold, the champion, the Philistine from Gath named Goliath, was coming up from the army of the Philistines, and he spoke these same words; and David heard them.
24 When all the men of Israel saw the man, they fled from him and were greatly afraid. 25 The men of Israel said, “Have you seen this man who is coming up? Surely he is coming up to defy Israel. And it will be that the king will enrich the man who kills him with great riches and will give him his daughter and make his father’s house [l]free in Israel.”
26 Then David spoke to the men who were standing by him, saying, “What will be done for the man who kills this Philistine and takes away the reproach from Israel? For who is this uncircumcised Philistine, that he should taunt the armies of the living God?” 27 The people [m]answered him in accord with this word, saying, “Thus it will be done for the man who kills him.”
28 Now Eliab his oldest brother heard when he spoke to the men; and Eliab’s anger burned against David and he said, “Why have you come down? And with whom have you left those few sheep in the wilderness? I know your insolence and the wickedness of your heart; for you have come down in order to see the battle.” 29 But David said, “What have I done now? Was it not just a[n]question?” 30 Then he turned [o]away from him to another and said the same thing; and the people answered the same thing as [p]before.
David Kills Goliath
31 When the words which David spoke were heard, they told them [q]to Saul, and he sent for him. 32 David said to Saul, “Let no man’s heart fail on account of him; your servant will go and fight with this Philistine.” 33 Then Saul said to David, “You are not able to go against this Philistine to fight with him; for you are but a youth while he has been a warrior from his youth.” 34 But David said to Saul, “Your servant was tending his father’s sheep. When a lion or a bear came and took a lamb from the flock, 35 I went out after him and [r]attacked him, and rescued it from his mouth; and when he rose up against me, I seizedhim by his beard and [s]struck him and killed him. 36 Your servant has [t]killed both the lion and the bear; and this uncircumcised Philistine will be like one of them, since he has taunted the armies of the living God.” 37 And David said, “The LORD who delivered me from the paw of the lion and from the paw of the bear, He will deliver me from the hand of this Philistine.” And Saul said to David, “Go, and may the LORD be with you.” 38 Then Saul clothed David with his garments and put a bronze helmet on his head, and he clothed him with armor.39 David girded his sword over his armor and tried to walk, for he had not tested them. So David said to Saul, “I cannot go with these, for I have not tested them.” And David took them [u]off. 40 He took his stick in his hand and chose for himself five smooth stones from the brook, and put them in the shepherd’s bag which he had, even in his pouch, and his sling was in his hand; and he approached the Philistine.
41 Then the Philistine came on and approached David, with the shield-bearer in front of him. 42 When the Philistine looked and saw David, he disdained him; for he was but a youth, and ruddy, with a handsome appearance. 43 The Philistine said to David, “Am I a dog, that you come to me with sticks?” And the Philistine cursed David by his gods. 44 The Philistine also said to David, “Come to me, and I will give your flesh to the birds of the sky and the beasts of the field.” 45 Then David said to the Philistine, “You come to me with a sword, a spear, and a javelin, but I come to you in the name of the LORD of hosts, the God of the armies of Israel, whom you have taunted. 46 This day the LORD will deliver you up into my hands, and I will strike you down and remove your head from you. And I will give the dead bodies of the army of the Philistines this day to the birds of the sky and the wild beasts of the earth, that all the earth may know that there is a God in Israel, 47 and that all this assembly may know that theLORD does not deliver by sword or by spear; for the battle is the LORD’S and He will give you into our hands.”
48 Then it happened when the Philistine rose and came and drew near to meet David, that David ran quickly toward the battle line to meet the Philistine.49 And David put his hand into his bag and took from it a stone and slung it, and struck the Philistine on his forehead. And the stone sank into his forehead, so that he fell on his face to the ground.
50 Thus David prevailed over the Philistine with a sling and a stone, and he struck the Philistine and killed him; but there was no sword in David’s hand.51 Then David ran and stood over the Philistine and took his sword and drew it out of its sheath and killed him, and cut off his head with it. When the Philistines saw that their champion was dead, they fled. 52 The men of Israel and Judah arose and shouted and pursued the Philistines [v]as far as the valley, and to the gates of Ekron. And the slain Philistines [w]lay along the way toShaaraim, even to Gath and Ekron. 53 The sons of Israel returned from chasing the Philistines and plundered their camps. 54 Then David took the Philistine’s head and brought it to Jerusalem, but he put his weapons in his tent.
55 Now when Saul saw David going out against the Philistine, he said to Abner the commander of the army, “Abner, whose son is this young man?” And Abner said, “By your life, O king, I do not know.” 56 The king said, “You inquire whose son the youth is.” 57 So when David returned from killing the Philistine, Abner took him and brought him before Saul with the Philistine’s head in his hand.58 Saul said to him, “Whose son are you, young man?” And David answered, “I am the son of your servant Jesse the Bethlehemite.”

Sources (1. http://www.jewishvirtuallibrary.org/jsource/History/Philistines.html)