In a dream, an angel revealed to Joseph that his betrothed wife Mary was carrying a child by the Holy Spirit, and not by another man. Thus, Joseph's concerns about her infidelity are laid to rest, and he is no longer planning to discreetly divorce her. Additionally, the angel says the baby is a boy, a son, who will save his people from their sins. It is the first of several references to Jesus' role as the Messiah prophesied in the Old Testament.
As Matthew explained, Joseph dreamed that he encountered an angel of the Lord. In spite of the fact that Mary and Joseph were ordinary people, they were not ordinary couples. They were chosen by God to raise His only begotten son at their simple home in Nazareth. Jesus was entrusted to them to bring Him to maturity and prepare Him for manhood and the tremendous task of redemption for which He was assigned. 
After Matthew presented a comprehensive genealogy and an unabridged, unflattering, and embarrassing account of Mary and Joseph's betrothal and Jesus's birth, he was finally prepared to reveal Jesus' role as Messiah. In a beautiful way, the glorious gospel of Jesus Christ ties into the many prophecies of the Old Testament.

Dear Heavenly Father, thank You for the free gift of salvation and for the many blessings You have lavished upon me by grace. Although I know You can provide for all my needs, I often doubt whether You will. Please teach me how to trust You in times of need and follow You more closely in faith. Give me a generous heart that gives cheerfully and willingly to others, regardless of my circumstances. When I don't have the resources to help others, help me to show compassion and kindness to those in need and to pray for them. We can trust You to provide for all our needs!
In Jesus's name I pray. Amen.