No they are not. There are demons, and people that dream of their relatives but there are not ghosts. The bible is quite clear that when you die your soul goes to heaven or hell. There is no getting around it.
Where, exactly is heaven?
There are many references in the Bible to spirits or ghosts.
1 Sam 28 - 7 Then Saul told his officers, “Find me a woman who can talk to the spirits of the dead. I’ll go to her and find out what’s going to happen.”
ESV Leviticus 19:31 - “Do not turn to mediums or necromancers; do not seek them out, and so make yourselves unclean by them: I am the LORD your God.
2 Kings 21:6 - 6 And he burned his son as an offering[a] and used fortune-telling and omens and dealt with mediums and with necromancers. He did much evil in the sight of the Lord, provoking him to anger.
Job 7:9-10, Deuteronomy 18:11, Psalm 146:4, Isaiah 8:19
So its in the Bible that the spirits exist. Yes some of them are clearly demons and some are angels but from the Bible it is clear not all are. What is clear is we should trust in God and not seek out spirits or ghosts. Nor do we need to fear them.