This prayer of Jesus for his followers and those who will believe in him through them is a fitting culmination to Jesus’ ministry, and leads on to the cross.
Verses 1-26: This is Jesus’ high priestly prayer. It falls naturally into three parts:

• Vv. 1-5: Jesus’ prayer for himself
• Vv. 6-19: His prayer for his disciples, left in the world after his ascension, and
• Vv. 20-26: His prayer for the Church universal. [ NOAB]

There are parallels to the Lord's Prayer. [ NJBC]
Verse 1: “looked up to heaven”: Presumably standing – the conventional Jewish attitude of prayer. See also 11:41; Luke 9:16; 18:13; Mark 6:41; 7:34; Matthew 14:19; 1 Enoch 13:5.
Verse 2: “you have given him authority”: To judge, lay down and take up his life. See also 5:27; 10:18; 19:10-11 (Jesus before Pilate); 3:27, 35.
Verse 4: “by finishing the work”: See also 4:34; 5:36; 19:28, 30.
Verse 4: “that you gave me to do”: See also 10:25.
Verse 5: “before the world existed”: See also 1:1ff; 8:58; 17:24.
Verse 6: “I have made your name known”: The Greek verb ephanerosa is used of the manifestation of Jesus, or of his glory, or of God’s works, in 1:31; 2:11; 9:3; 21:1, 14. Here it is to those given to Jesus by the Father that Jesus, by his words and deeds, makes known God’s “name”, i.e. his character and person. [BlkJn]
Verse 7: “‘everything you have given me’”: i.e. the entire ministry of Jesus with all that this involves. [BlkJn]
Verse 8: “‘for the words ...’”: Jesus’ words are the Father’s words: 3:34 says “He whom God has sent speaks the words of God, for he gives the Spirit without measure”. See also 7:16; 12:49-50; 14:10, 24. [BlkJn]
Verse 8: “they ... know in truth that I came from you”: See also 16:27. In context, Jesus does not merely mean that he is Messiah, far less that he is a superman, one of the divine heroes of the ancient world, but that his claims to pre-existence (see v. 5) are justified. [ BlkJn]
Verse 9: “‘I am not asking on behalf of the world, but on behalf of those whom you gave me’”: Others are not capable, unless they come to faith in Jesus (see v. 20), of sharing in what the Father gives. [ BlkJn]
Verses 11-12: 13:1 tells us that Jesus’ departure is imminent: “Now before the festival of the Passover, Jesus knew that his hour had come to depart from this world and go to the Father ...”. On the disciples being left exposed to the hostility of the world, in 15:18 Jesus says “If the world hates you, be aware that it hated me before it hated you”. See also 17:14 and 16:1-5a (for an alternative presentation of the ideas). [BlkJn]
Verse 11: The unity of believers is modelled on the shared purpose and character of the Father and the Son, who are in complete unity. [ BlkJn]
Verse 12: “‘the scripture’”: That “scripture” is in the singular implies that John has a particular passage in mind. It may be Psalm 41:9 (“Even my bosom friend in whom I trusted, who ate of my bread, has lifted the heel against me.”), which Jesus quotes in 13:18. [ BlkJn]
Verse 12: “the one destined to be lost”: This phrase is also found in 2 Thessalonians 2:3; there it refers to the Antichrist. [ BlkJn]
Verse 14: “‘word’”: See also 1:1-19: “In the beginning was the Word, and the Word was with God, and the Word was God...”.
Verse 17: “your word is truth”: God’s “word” (Greek: logos) is the means of sanctification. The Father’s “word” is characterized as the revelation of ultimate reality. 1:14 says that the incarnate “Word”, Jesus, is “full of grace and truth”. The “truth” sets free those who persevere in Jesus’ word: see 8:31-36. [ BlkJn]
Verse 18: In 20:21, in his appearance to the disciples, Jesus tells them: “As the Father has sent me, so I send you”. [ BlkJn]
Verse 19: “‘sanctify myself’”: In the Septuagint translation, the Greek verb agiadzo (“sanctify”) is used both for the setting apart for God (in Exodus 3:2 and Deuteronomy 15:19) and for the consecration of people to God’s service (in Jeremiah 1:5, of a prophet, and in Exodus 28:41, of priests). Christ’s perfect self-offering is the means by which the disciples whom he is sending into the world are dedicated in obedience to God. [ BlkJn]