Core Concepts and Language Structure At its heart, C is procedural: programs are collections of functions that operate on data. The basic building blocks include variables, data types, expressions, control structures (if, switch, for, while, do-while), functions, arrays, pointers, structures, and file I/O. C’s primitive types (char, int, float, double) and user-defined types (struct, union, enum, typedef) let programmers model data concisely. C’s operators and precedence rules, combined with explicit memory semantics, give fine-grained control but demand attention to detail.