Learn in the textbookEconomic Evaluation
DefinitionOperating cost (運用コスト) is money that keeps being spent to run and maintain a system for as long as it is in use; it is also called running cost (ランニングコスト).
ExplanationElectricity and communication charges, maintenance fees for hardware and software, and the wages of the staff who operate the system all fall here. These costs arise every month or year, so the longer the system is used, the larger the running total grows.
AnalogyIt is like the utility bills and repair costs of a home you live in. They come every month as long as you stay, and the sum swells the more years you live there.
Memory hookランニング is the English word running, "keeping on going." Remember it as the cost that never stops while the system keeps working.