"Statements" primarily have the role of steering the "control flow" (the order of execution).
This is done through "control structures" such as if-else, for, while, switch, goto, try-catch, guard, etc. statements.
Statements always exist within the body of a function, or within the confines of a "meta construct", never in global or declaration scope. Cosmos does have special "meta statements" that can exist in declaration scope. More on that later.
Statements are themselves made from other statements and "expressions".
The sub-pages each describe how different kinds of statements alters the control flow, and under what conditions.