In Deuteronomy, when God is giving Moses the good news that his people will be led by God into a rich land where they will prosper, he also warns him to be careful to always give God the credit, or they would become proud, taking credit for the good, and forgetting God.
That's basically what pride is: forgetting God.
More specifically, pride is the turning away from God to find satisfaction in yourself.
Covetousness is a turning away from God to find satisfaction in things. Greed is a turning away from God to find satisfaction in money. Impatience is a turning away from God to find satisfaction in "getting things done" quickly. Anger or hate is a turning away from God to find satisfaction in my perception of justice. Lust is a turning away from God to find satisfaction in sex.
Pride is like these, but deeper, perhaps even underneath and the cause of all of them. Self-exaltation, self-satisfaction, and self-determinism are the roots sustaining all deadly sins. In Leviticus 26:19, God says that He will go to any lengths in order to break pride. He has no use for it in His people. And He knows just how deadly it is.
We can join Him in detoxing our lives of pride. We can position ourselves to allow God to "lift us up" rather than "bring us down." How?
Humble yourself (which is simply to make much of God instead of you). Jesus' brother says it best: "God opposes the proud but gives grace to the humble." (James 4:6)