What are angels according to the Bible?

TL;DR:

According to the Bible, angels are spirit beings, created for God’s purposes. Angels obey God and worship Him; we are called to do the same.

According to the Bible, angels, both fallen and non-fallen, are created, spirit beings who serve as messengers and servants of God (Nehemiah 9:6; Hebrews 1:14). They do not possess physical bodies but can take on physical forms when needed (Genesis 19; Hebrews 1:14). Angels are intelligent and emotional beings with individual personalities and wills (Matthew 8:29; Luke 2:13). Holy angels execute God’s will, serving as messengers, protectors, and ministering spirits. Angels recognize God for who He is, and angels that did not fall, worship Him (Isaiah 6:1–3; Revelation 5:11–14). Seeing the angels’ response to God encourages us to recognize God and worship Him for who He is and to live out His will in our lives.

from the old testament

Angels are created beings (Nehemiah 9:6; Colossians 1:16). They are an entirely separate type of creature from humans.
Angels are spirit beings (2 Kings 6:16–17) and do not have physical bodies though it appears that they can take on physical form (Genesis 19:1).
Angels stand before God in His presence (Job 1:6; 2:1).
In the Old Testament, angels are often described as executing God's will and delivering His messages. For instance, an angel or the Angel of the Lord stopped Abraham from sacrificing Isaac (Genesis 22:11–12), angels visited Lot to warn him of Sodom's destruction (Genesis 19:1–22), and an angel provided food and encouragement to Elijah (1 Kings 19:5–7).
Angels are also described as worshiping God. In Isaiah 6:1–3, the seraphim are depicted as standing above God's throne, calling out to one another, "Holy, holy, holy is the LORD of hosts; the whole earth is full of his glory!" Similarly, in Nehemiah 9:6, it is mentioned that the "host of heaven" worships God.
Neither good or evil angels possess limitless knowledge (Job 38:4–7; see also 1 Peter 1:12). They cannot be everywhere at once, and they are not as powerful as God (Job 1:6–7).
Angels understand humanity very well having lived since the days of old.
The Bible never says that angels are created in God's image, as humans are (Genesis 1:26).

from the new testament

The New Testament provides various insights into the nature, roles, and activities of angels. Angels, both fallen or non-fallen, are described as intelligent beings (Matthew 8:29; 2 Corinthians 11:3; 1 Peter 1:12), they are emotional beings (Luke 2:13; James 2:19; Revelation 12:17), and each has an individual personality and will (Luke 8:28–31; 2 Timothy 2:26; Jude 1:6).
The New Testament also describes angels as spirit beings (Hebrews 1:14) that can take human form (Acts 1:10–11; Hebrews 13:2).
The New Testament reveals angels as messengers (Luke 1:26–28), ministering spirits (Hebrews 1:14), and spirits that provide protection to humans (Acts 12:7).
Angels, like all created beings, are subject to the will of God and fulfill God’s purposes. Angels are mobilized by God to come to the aid of believers (Hebrews 1:14) and do many other things as well, including praising and worshiping Him (Hebrews 1:6; Revelation 5:8–14). The angels rejoice in God's works, and they serve Him (Revelation 22:9). They proclaim God's judgments (Revelation 7:1, 8:2). They minister to humans and sometimes bring answers to prayers (Acts 8:26; 10:3; 12:5–10). They watch Christians' work and sufferings (1 Corinthians 4:9; 11:10; Ephesians 3:10; 1 Peter 1:12). They encourage (Acts 27:23–24), and they care for believers when they die (Luke 16:22).
The angels created at the beginning of time who are loyal to God are still with God (Matthew 18:10; Revelation 5:11). The angels that fell at the beginning are still fallen, some kept in chains until the judgment day (2 Peter 2:4). Both holy angels and demons (fallen angels) are able to come to earth.
Angels understand the Bible and the world, and they believe in the prophecies of God (James 2:19; Revelation 12:12). Even the fallen angels, who hate God, are not atheists; they know that God exists (Mark 1:23–24; James 2:19).
The New Testament also confirms that both good and evil angels do not possess limitless knowledge (Matthew 24:36) and are not as powerful as God (Hebrews 1:4–5).
There are a limited number of angels, and they do not reproduce (Matthew 22:30; Luke 20:34–36).
Satan (Lucifer) is still just an angel, a created being, and even though he has power as the ruler of the world (John 12:31), he is nowhere near as powerful as God. His demise is sure (Revelation 20:10).

implications for today

The holy angels offer us a profound example of how to live out our faith through their submission to God and reverence for His majesty. Their unwavering obedience to God's authority prompts us to reflect on where we might be resisting His will in our own lives. Isaiah 6:3 portrays the seraphim's relentless proclamation of God's holiness, urging us to adopt a similar awe and recognition of His supreme sovereignty. Seeing God for who He is and surrendering our lives to Him completely transforms our daily actions, infusing them with humility, reverence, awe, and a deeper commitment to God's purposes. By mirroring the angels' devotion and reverence, we draw nearer to God's will and find renewed strength and direction in His divine presence.

understand

Angels are created spirit beings who serve God and can take on physical forms.
Angels have intelligence, emotions, and individual wills, and they execute God's will and worship Him.
Both good and evil angels have limited knowledge, are not omnipresent, and are not as powerful as God.

reflect

How does understanding angels impact your view of how God interacts with His creation?
How does the holy angels' unwavering obedience and worship of God inspire you to align your life more closely with God's will and purpose?
How does the limitation of angels’ abilities influence your trust in God's sovereignty?

engage

How can we apply the example of angels worshiping and serving God in our own lives?
What are some characteristics of angels that we can emulate in our own walk with God?
How does the limited knowledge of angels shape our understanding of spiritual and physical matters today?