To define the term ‘non-current assets’ requires that we address the concept of liquidity. An asset is liquid if it can be realized within a short period of time and with ease without losing any of its value (normally assumed within a year). Liquid assets comprise your company’s ‘current assets’. However if an asset is not as liquid due to its nature and its use for your company, it’s treated as a ‘non-current asset’ on your company’s balance sheet. 

Non-current assets (usually property, plant and equipment, software (that is intangible assets)) are those that you’d use for a longer period than just a year and more so, they’re normally considered not that easy to be realised. As it is, with such assets there are different treatments than you’d have for current assets (also for current assets which in part are realized after a year and are thus also recognized under non-current assets). Assets like property, plant and equipment aren’t your usual collectable receivables or prepaid balances to be realized in as expenses or inventories. I guess the biggest addition to accounting treatments when it comes to property, plant and equipment is the fact that they’re being depreciated into expenses. As with every assets, they’re obviously written down in value should the situation require, they can be sold and scrapped (similar to inventories no longer in use) and so on.

And remember that it’s actually best to have some assets recognized as your property, plant and equipment as opposed to just shoving them into expenses in order not to stress you with the treatment of one.