Here's why:

* Sticky ends: They are called this because they are single-stranded overhangs that can base pair with complementary sequences on other DNA molecules. This "stickiness" allows for easy joining of DNA fragments during cloning or other genetic engineering techniques.

* Cohesive ends: This term emphasizes the ability of these overhangs to bind to each other due to their complementary base pairing.

It's important to note that there are also blunt ends, which are double-stranded ends with no overhangs. These are less efficient for joining DNA fragments compared to sticky ends.