BestFit is selecting the area that fits the closest.
BestFit tends to be slow, and, if allocations are of dynamic size tends to lead to having lots of very small spaces left free. For instance, if there are a 10 byte, 20 byte or 30 byte region free and you are trying to allocate "9" bytes, you will use the 10 byte region leaving 1 byte, 20 byte and 30 bytes free. The 1 byte region is unlikely to be allocated.
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