GC (Garbage Collection)

Garbage collection (GC) is a mechanism that automatically detects and frees portions of memory a program temporarily allocated while running once they're no longer referenced and therefore unneeded.
Put simply, it acts like a "trash collector" inside a computer.
Memory capacity is limited, so if unused data is left in place, there's eventually no room for new data, which can cause the program to stall.

There's more than one way to manage memory in languages without GC. In C, for example, developers write code themselves to explicitly return each block of memory once it's no longer needed, while in Rust the language automatically returns memory as soon as a variable's role ends.
With the former approach, forgetting that instruction easily causes a "memory leak," where available memory keeps shrinking.
GC became widely adopted as a way to watch actual memory usage during execution, judge that certain data is no longer reachable from anywhere, and reclaim it as trash.

Specifically, the system targets data no longer traceable from any variable and dynamically reclaims it, for instance when free memory runs low for placing new data.
This frees developers from fine-grained memory management so they can focus on building the program itself.
However, since collection can briefly pause the program for an instant, extra care is sometimes needed in cases like games that demand very high speed.