diff --git a/inc/definition.h b/inc/definition.h
new file mode 100644
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--- /dev/null
+++ b/inc/definition.h
@@ -0,0 +1,62 @@
+
+#ifndef CARROT_DEFINITION_H
+#define CARROT_DEFINITION_H
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+// carrot_definition_unit_s: A whole file (with possible included sub-files) of rules.
+//  A definition unit describes a single format or language.
+typedef struct      carrot_definition_unit              carrot_definition_unit_s;
+
+// carrot_rule_definition_s: The definition of a rule with all of the patterns it contains.
+//  A rule definition starts with the name of the rule inside of a pair of arrow brackets ( < > ),
+//  followed by an equals sign and some patterns, until a semicolon ends the rule definition.
+typedef struct      carrot_rule_definition              carrot_rule_definition_s;
+
+// carrot_pattern_s: A pattern consisting of a sequence of pattern elements. These elements
+//  can be terminal or the names of whole other rules themselves.
+typedef struct      carrot_pattern_sequence             carrot_pattern_sequence_s;
+
+// carrot_pattern_element_s: An element of a pattern; this can be a terminal symbol or the name
+//  of another rule in arrow brackets ( < > ). It denotes a piece of data, one or multiple tokens,
+//  which have to exist for the pattern to begin (which are static, defined literals)
+//  or can be extracted (like variable terminals).
+typedef struct      carrot_pattern_element              carrot_pattern_element_s;
+
+// carrot_terminal_s: An ending symbol of the parsing tree. This can be the name of a variable terminal
+//  or a static, defined literal.
+//
+//  A variable terminal could be "[word]", "[keyword]" or one of some others (as they are defined in
+//  docs/variable_terminals.md)
+//
+//  A static, defined literal is a literal piece of data which must exist at that position in a rule
+//  in exactly the way as it was stated in the definition.
+typedef struct      carrot_terminal                     carrot_terminal_s;
+
+struct carrot_definition {
+
+};
+
+struct carrot_rule_definition {
+
+};
+
+struct carrot_pattern {
+
+};
+
+struct carrot_pattern_element {
+
+};
+
+struct carrot_terminal {
+
+};
+
+
+
+#endif