Angels are spiritual beings:
Who makes His angels spirits, His ministers a flame of fire. (NKJV)
... to the intent that now the manifold wisdom of God might be made known by the church to the principalities and powers in the heavenly places ... (NIV)
Then a spirit passed before my face;
The hair on my body stood up.
It stood still,
But I could not discern its appearance.
A form was before my eyes;
There was silence;
Then I heard a voice saying:
‘Can a mortal be more righteous than God?
Can a man be more pure than his Maker?
If He puts no trust in His servants,
If He charges His angels with error ... (NKJV)
And I fell at his feet to worship him. But he said to me, “See that you do not do that! I am your fellow servant, and of your brethren who have the testimony of Jesus. Worship God! For the testimony of Jesus is the spirit of prophecy.” (NKJV)
How you have fallen from heaven,
O morning star, son of the dawn!
You have been cast down to the earth,
you who once laid low the nations!
You said in your heart,
"I will ascend to heaven;
I will raise my throne
above the stars of God;
I will sit enthroned on the mount of assembly,
on the utmost heights of the sacred mountain.
I will ascend above the tops of the clouds;
I will make myself like the Most High." (NIV)
And the angels who did not keep their positions of authority but abandoned their own home—these he has kept in darkness, bound with everlasting chains for judgment on the great Day. (NIV)
1 Peter 3:22
... who has gone into heaven and is at the right hand of God, angels and authorities and powers having been made subject to Him. (NKJV)
... while the morning stars sang together and all the angels shouted for joy? (NIV)
1 Peter 1:12
It was revealed to them that they were not serving themselves but you, when they spoke of the things that have now been told you by those who have preached the gospel to you by the Holy Spirit sent from heaven. Even angels long to look into these things. (NIV)
Then he continued, "Do not be afraid, Daniel. Since the first day that you set your mind to gain understanding and to humble yourself before your God, your words were heard, and I have come in response to them. But the prince of the Persian kingdom resisted me twenty-one days. Then Michael, one of the chief princes, came to help me, because I was detained there with the king of Persia. (NIV)
The chariots of God are tens of thousands and thousands of thousands ... (NIV)
But you have come to Mount Zion, to the heavenly Jerusalem, the city of the living God. You have come to thousands upon thousands of angels in joyful assembly ... (NIV)
Then I looked and heard the voice of many angels, numbering thousands upon thousands, and ten thousand times ten thousand. They encircled the throne and the living creatures and the elders. In a loud voice they sang: "Worthy is the Lamb, who was slain, to receive power and wealth and wisdom and strength and honor and glory and praise!" (NIV)
Page 3: What Do Angels Do?
Page 4: Names and Descriptions of Angels