In operating system context, segmentation and paging both are memory management techniques.
As Paging is known as one of the best memory management technique but still it has some problem i.e. internal fragmentation. In paging technique, whole physical memory is divided into fixed size i.e frames and the process is divided into the pages where each page size is equal to frame size. It may be last page of process in not fit into frame, I mean to say page size is smaller than frame size. In that case memory of that frame can't be used fully. That problem is known as internal fragmentation.
To solve this problem another technique is proposed which is known as segmentation. This technique tells that divide a process logically like data segment, code segment etc. And allocate memory to each segment.
This way, internal fragmentation problem can be solved and at the same there is no need of a huge chuck of memory to keep the complete process in memory.
