What's "self-contained" mean? Is this a commonly used term?

Native speaker’s answer
Rebecca
To be "self-contained" means to be complete or having all that is needed in itself. The speaker in this video describes these books of essays as being "self-contained," meaning that they are already complete on their own, so there is less motivation to finish the whole book. Ex: The house was self-contained. It had its own power generator and garden for food. Ex: The ecosystem was self-containing and self-sustaining.