What characterizes the process called oxidation?

Oxidation is characterized by the process of losing electrons. This fundamental concept in chemistry is crucial for understanding redox (reduction-oxidation) reactions, where oxidation and reduction occur simultaneously. When an atom or molecule undergoes oxidation, it increases its oxidation state, which typically means it has lost one or more electrons.

In a redox reaction, as one species loses electrons (is oxidized), another species gains those electrons (is reduced). For instance, when iron reacts with oxygen, iron loses electrons and is oxidized to form iron oxide (rust). This transfer of electrons is a key element of chemical reactivity and energy changes in reactions.

The other options provided in the question do not accurately describe oxidation. Gaining electrons would indicate a reduction, gaining protons or losing protons does not apply directly to the electron transfer process that defines oxidation. Thus, understanding that oxidation specifically involves the loss of electrons helps in grasping the broader context of electron transfer processes in chemistry.