Property, Plant, and Equipment is the total value of a business' most essential assets, which cannot easily be liquidated
Property, plant & equipment (PP&E) are those assets essential to the company's business including (as the name suggests) the property on which the company does business and the equipment essential for the business' continued operations. Often, PP&E assets are tailored to be production specific and as such have little resale value. Over time, the value of these assets are generally depreciated to more accurately reflect their current worth to the company. The term "fixed assets" is often used in place of "property, plant and equipment" and the two terms are functionally equivalent.
It should be noted that while most PP&E assets (such as motor vehicles or computers) depreciate over time, land and buildings can often increase in value depending on local real-estate conditions.
Because PP&E assets are highly illiquid, investors often use the metric as a gauge of how quickly a company can adapt to dramatic shifts in the industry. In theory, companies with high PP&E relative to their total book value are less capable of adapting quickly to new and emerging trends, as they are incapable of converting assets acquired or developed for very specific purposes into cash or other, newly necessary assets.