The popular view is that the 8th Commandment, Lo Tignov, refers to stealing property. The sages point out, however, that there are other sources about stealing things, and this verse means stealing a person.
Obviously all forms of stealing are prohibited. Whoever steals a thing or person regards him- or herself as higher than God. God ordains who is the owner; the thief says, “I know better”. It’s an example of the Tower of Babel syndrome. The builders of Babel thought they should be running the universe, not God.
These days the people who don’t want to believe in God or accept His rule think they can make the decisions and re-allocate rights at will. Whether they act individually or as a group, they cause anarchy and make social life impossible.
What is meant by stealing a person? Not only kidnapping, though that is bad enough. It also denotes robbing a person of their heritage; the victims include the Jewish children who were placed with gentiles during the Holocaust and never given back to Judaism. In Australia the Aboriginal children who were forced into the white community are known as The Stolen Generation.
Ramban says that the 8th Commandment is linked with the 7th (the ban on adultery) in that adultery denies a child the knowledge of its real father. Rav Soloveitchik includes in the 8th Commandment a duty not to rob a person of their self-respect.