Angels are spiritual beings -- that is, they don't have physical bodies that we can see or touch. The Bible calls them "ministering spirits sent to serve those who will inherit salvation" (Hebrews 1:14).
At times, however, they can assume physical form -- and when that happens, they can be seen by us. The Bible indicates this happens only rarely -- but it does happen. At times, their appearance is glorious and radiant, and they are immediately recognized as angelic beings. At the end of the present age, for example, the Bible says that the angelic hosts of heaven will accompany Christ as He comes again in glory (see Matthew 25:31). At other times, however, they are unrecognized because they appear as ordinary humans. The Bible says that "some people have entertained (or welcomed) angels without knowing it" (Hebrews 13:2).
We should take great comfort in the fact that we are never alone if we know Christ. We are never alone because He lives within us by His Holy Spirit -- but we also are never alone because His angels are constantly with us. The Bible says, "He will command his angels concerning you to guard you in all your ways" (Psalm 91:11).
At the same time, we are not to worship the angels or make them the center of our attention. Christ alone is our Savior, and He alone is worthy of our faith. Is He the center of your life?