I don't know why color path and masking are used in Adobe Photoshop.

So, Will you kindly answer me of the questions.

Paths are vector selections used to separate an image into 2 areas. They are useful because they can be any shape which makes them perfect for separating a background from the foreground. They are also used for making custom vector shapes for later use.

Masking is also used to make selections from an image. The selections do not need to be continuous and can contain varying degrees of opacity.

Let me know what your specific questions are and I can answer them less generally.