Eli5 – Equity locked in houses

Question

While reading through big short , I came across this sentence, ‘People with first mortgages had vast amounts of equity locked up in their houses’. What does this mean.

In: 1

Answer 1

With regard to the big short I think they may have been referring to the equity that is gained from the asset appreciating in value due to market conditions/demand/speculation. In some markets houses were like doubling in a few years.