The name Mark is actually a surname, his common name being John (Acts 12:12; 13:5; n, 4:11). Since he was related to Barnabas (Col. 4:10), Mark may have been a Levite (4:36) Mark travelled with the Apostle Paul and Barnabas on their first missionary journey (Acts 12:25), but he turned back (Acts 13:13). For this reason, Paul refused to consider taking him along on the second missionary journey (Acts 15:36 -39).  Paul and Barnabas had such a strong disagreement about the matter that they decided to go different directions, Paul with Silas and Barnabas with Mark. Later Paul and Mark were reconciled (Col. 4:10; Phile. 1:24), and Paul came to regard Mark as one who was "profitable . . for the ministry" (2 Tim. 4:11).

The contents of the book and extra-biblical sources indicate that Mark's Gospel was written for the benefit of those who lived outside Palestine. These people who had not witnessed the events of Jesus life would profit most from Mark's emphasis on the supernatural power of Jesus. 

His actions, rather than His words, are given the most attention, particularly the miracles He performed which demonstrated His divinity. The narrative moves swiftly from one stirring scene of Jesus' ministry to another without interruption. The rapid pace can be seen in the frequent use of the transitional Greek word euthéos (2117), meaning "immediately" or "straightway" (used 40 times).
It is generally accepted and supported by the writings of the church historians that Peter was Mark's source for the information contained in his Gospel. Since the book was probably written from Rome immediately after Peter's death, the date for its writing is presumed to be A.D. 67 or 68.

The Book of Mark, being written earlier than the other Gospels, has ninety-three percent of its material repeated in Matthew and Luke, many times using the same words. The details that Mark gives in his brief account, however, are more graphic than in the other accounts. [Source for Introduction of chapter: Hebrew Greek Key Study Bible KJV edited by Spiros Zodhiates, Th.D. AMG Publishers, Chattanooga, TN 37422]

Observations from Mark (Supplement to Matthew where main points given to avoid repetition).
1:4, new method ushered in prior to doing away of animal sacrifices and destruction of temple in A.D. 70. v5 they confessed sins as were baptised. (1Jhn 1:9)
1:23 Man with unclean spirit (i.e. of satan) calmly in the synagogue learning, how those in the synagogue reason and think.  2Co 11:13 For such are false apostles, deceitful workers, transforming themselves into the apostles of Christ. 2Co 11:14 And no marvel; for Satan himself is transformed into an angel of light. Thus believers or would be believers can be deceive, if not already done so in past that now they adhere to customs of men?

1:32 People wait until after Sabbath to come to Jesus for healing. Many possessed by satan weekly in synagogues.
2:7 To claim ability to forgive sins is blaspheme for all men except Jesus (son of God).  2:27 Sabbath made for man’s benefit.
Chapter 3 see Comments on Matthew for most points. 3:29 unforgivable sin.
Chapter 4 Note 4:11-12,34. 4:21 Let your light shine, knowledge of God be shared with others. You were bought / converted to teach others. Come abroad means spread far and wide beyond your locality. V24 Take heed of what Christian message you hear. Those with proper knowledge will be given more and those without, even what they have will be taken away from them.

5:7 the possessed man has two beings within him. His own and that possessing him. Who ran to Jesus asking not to be tormented? Who “adjured by God”?
5:39 Servants told father his daughter was “dead”, Yahshua / Jesus called it sleep. When humans die the 1st death from this world, it is a sleep until the day of judgement of all by Yahshua at His second coming. They do not go directly to heaven or hell otherwise they would be no need for Yahshua to return and judge. Those who do not get into heaven after day of judgement at end of world suffer the 2nd real death in lake of fire with satan.. (See Rev 2:11 He that hath an ear, let him hear what the Spirit saith unto the churches; He that overcometh shall not be hurt of the second death. Rev 20:6 Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years. Rev 20:14 And death and hell were cast into the lake of fire. This is the second death. Rev 21:8 But the fearful, and unbelieving, and the abominable, and murderers, and whoremongers, and sorcerers, and idolaters, and all liars, shall have their part in the lake which burneth with fire and brimstone: which is the second death).

5:43 Jesus concealed His miracles not publicise them as today’s so called “healers”.
6:1 Again Jesus always in synagogue on Sabbath and never once taught them it was to end at any time; even after His death. 6:3 heard the good teachings yet offended because He was one of them. Hence Jesus’ saying in v4. V5 due to their unbelief He could not do His great works. V13 disciples already had power to heal etc before Holy Spirit fell on them for purpose of day of Pentecost (to be able to communicate the gospel / good news of the arrival of the Messiah to those gathering in Jerusalem and who spoke various languages).

6:14 Note the belief of rising from dead immediately after death, even as a mature man was a pagan (Egyptian) belief. True Christians believe in life after death at the 2nd coming of Christ at the end of the world. V21 Note Herod had other “lords”. V26 Everywhere in bible it is shown in old and New Testaments a kings oath cannot be changed otherwise he would not have any credibility. Thus neither does God’s commandments. If they could have been changed, God would not have sent His son to die, simply change or abolish the commandment.

6:30-34 could this be John Baptist followers now without a sheep who flocked to Jesus. John [prepared the way for them to be drawn to the real Lord?