what are the advantages of segmentation in 8086 microprocessor? Not getting the importance of segmentation. Is it for managing more memory?
The instruction set used in 8086 is a 16-bit instruction set. This means that a register can only store values in the range 0x0000 to 0xFFFF, and instructions mostly only did 16-bit operations (16-bit addition, 16-bit subtraction, etc). If a register contains an address/pointer, then it would've worked out to a maximum of 64 KiB of address space (some for ROMs, some for RAM) and this wasn't enough for the market at the time.
Segmentation was a way to allow the 16-bit CPU to support a larger address space. Essentially, combining two 16-bit registers together, so that addresses/pointers could be much larger. Unfortunately (likely, to avoid "unnecessary at the time" costs of having more address lines on the CPU's bus), instead of using two 16-bit registers as a 32-bit address, Intel did an "address = segment * 16 + offset" thing to end up with a 20-bit address, giving the 8086 a 1 MiB address space.
Later (early 1980s) there was a push towards "protected objects" where "objects" (in object oriented programming) could be given access controls and limits that are enforced/checked by hardware, and around the same time there were "virtual memory" ideas floating around. These ideas led to the ill-fated iAPX 432 CPU; but also led to the idea of associating protection (attributes and limits) to the segments that 8086 already had, which resulted in the "protected mode" introduced with 80286 (and extended in 80386).
Essentially; the original reason for (advantage of) segments was to increase the address space (without the cost of a 32-bit instruction set, etc); and things like protection and memory management were retro-fitted afterwards (and then barely used by software before being abandoned in favour of paging).