Final answer:
A disk cleanup utility or tool is a program used to remove unnecessary files from a hard drive, potentially including a defragmentation feature to optimize system performance.
Step-by-step explanation:
The program designed to un-clutter a hard drive is commonly known as a disk cleanup tool or utility. When you use such a tool, it helps in removing unnecessary files that accumulate over time, such as temporary files, system cache, or files in the recycle bin. Additionally, a disk cleanup utility may help to defragment the hard drive, which reorganizes the data in a manner that makes it easier for the computer to access and can improve overall system performance.
Some popular disk cleanup tools include the built-in Windows Disk Cleanup utility, CCleaner, and for Mac users, CleanMyMac. Using these tools routinely can help maintain the efficiency of your computer and prevent slowdowns caused by excessive clutter.