Having different physical characteristics, such as blue eyes or brown hair, are called traits. Traits are how we see the presence of different alleles. Your genes and DNA are too small for you to see, but you can see the physical traits they have given you (for example, a certain hair or eye color). Heredity is how these traits are passed on from one individual to their children, and then to their children.

Hybrid can be used to define a few different things. Basically, a hybrid is the offspring produced by breeding two different animals. This is often done to try and mix two desirable traits, such as by crossing (breeding) two different rose bushes, one that has a beautiful color but not smell, and another that has a nice smell but is not that pretty. By doing such a cross, someone can try to create a superior rose bush with both a beautiful flower and a nice smell.

Hope that helps answer your good and interesting questions! Genetics is a very big field and not everything in it is understood, but we have come a long way in understanding why we are how we are thanks to it.

A trait is a single characteristic that is usually assumed to be controlled by a gene, although many traits are controlled by more than one gene. The color of the pigment in the front of the eye is itself dependent upon other genes - usually it's brown, but it can be green, hazel, and in rare cases yellow or even violet. If you don't express the pigment at all, then your eyes will be blue (or blue-gray, because there is another pigment in the back of the iris that is controlled by yet more genes). So there are actually a number of genes that control eye color, some that make the color in the front of the iris, others that make the color in the back of the iris, and yet one more that can turn the color in the front of the iris on and off, thereby determining whether you see the pigment in the back or not.

A hybrid is something different entirely. If you have two populations that are quite different, it may still be possible to interbreed them and create an individual that has traits of both. For example, horses and donkeys are closely related but different species, but it is possible to breed them together to create a mule.

It is possible to make hybrids on many different scales - for example, a golden retriever and a black Labrador are two breeds of dogs, but the mutt that you could get by breeding them together is quite capable of having puppies itself, whereas a mule is sterile. But the mutt is a hybrid, because it's neither breed of its parents, but a mixture of both. (if you're wondering what such a dog would look like, imagine a golden retriever that has been dipped in black ink. Now, you can test your understanding of recessive versus dominant traits if you can say which alleles for hair length and hair color are dominant and recessive, respectively!)