Difference Between Multi‐core processor ，Dual‐core processor and Quad‐core processor

Multi‐core processor

A multi-core processor is a single computing component with two or more
independent actual processors (called "cores"), which are the units that read
and execute program instructions. The instructions are ordinary CPU
instructions such as add, move data, and branch, but the multiple cores can
run multiple instructions at the same time, increasing overall speed for
programs amenable to parallel computing. Manufacturers typically integrate
the cores onto a single integrated circuit die (known as a chip multiprocessor
or CMP), or onto multiple dies in a single chip package.

A many-core  processor is a multi-core processor in which the number of cores is large
enough that traditional multi-processor techniques are no longer
efficient[citation needed] — largely because of issues with congestion in
supplying instructions and data to the many processors. The many-core
threshold is roughly in the range of several tens of cores; above this threshold
network on chip technology is advantageous.

 Dual-core and Quad-core

A dual-core processor has two cores (e.g. AMD Phenom II X2, Intel Core Duo),
a quad-core processor contains four cores (e.g. AMD Phenom II X4, Intel's quadcore
processors, see i3, i5, and i7 at Intel Core)