What are halides? What are some examples of them?

The halogen elements are diatomic molecules, #X_2#, that can be easily reduced:

#X_2 + 2e^(-) rarr 2X^-#

The anions are the so-called halides: #F^-, Cl^-, Br^-, etc.#

Of course, if you have a negatively charged species, there must be a positively charged species as well to balance the charge, typically a metal cation, #Na^+#, #Mg^(2+)# etc. The best known halide is the stuff you put on your fish and chips :

Of course, I could broaden my horizons a little bit, and consider organic halides. A halogen atom can be tacked on to an alkyl or hydrocarbyl group to give an organic halide, where the halide takes the place of a hydrogen. With hydrocarbons, this is usually the first step of a synthesis, because once the halogen group is introduced (#Cl# or #Br#), you can start doing selective chemistry on the organic chain.