diff --git a/src/org/nwapw/abacus/function/Operator.java b/src/org/nwapw/abacus/function/Operator.java
index 6d6f7ff..c69f9d2 100644
--- a/src/org/nwapw/abacus/function/Operator.java
+++ b/src/org/nwapw/abacus/function/Operator.java
@@ -9,6 +9,10 @@ public class Operator {
      * The associativity of the operator.
      */
     private OperatorAssociativity associativity;
+    /**
+     * The type of this operator.
+     */
+    private OperatorType type;
     /**
      * The precedence of the operator.
      */
@@ -24,7 +28,7 @@ public class Operator {
      * @param precedence the precedence of the operator.
      * @param function the function that the operator calls.
      */
-    public Operator(OperatorAssociativity associativity, int precedence, Function function){
+    public Operator(OperatorAssociativity associativity, OperatorType operatorType, int precedence, Function function){
         this.associativity = associativity;
         this.precedence = precedence;
         this.function = function;
@@ -38,6 +42,14 @@ public class Operator {
         return associativity;
     }
 
+    /**
+     * Gets the operator's type.
+     * @return the type.
+     */
+    public OperatorType getType() {
+        return type;
+    }
+
     /**
      * Gets the operator's precedence.
      * @return the precedence.
diff --git a/src/org/nwapw/abacus/function/OperatorType.java b/src/org/nwapw/abacus/function/OperatorType.java
new file mode 100644
index 0000000..d003c07
--- /dev/null
+++ b/src/org/nwapw/abacus/function/OperatorType.java
@@ -0,0 +1,8 @@
+package org.nwapw.abacus.function;
+
+/**
+ * The type of an operator, describing how it should behave.
+ */
+public enum OperatorType {
+    BINARY_INFIX, UNARY_POSTFIX
+}
diff --git a/src/org/nwapw/abacus/plugin/StandardPlugin.java b/src/org/nwapw/abacus/plugin/StandardPlugin.java
index 01b988e..4cd13b5 100755
--- a/src/org/nwapw/abacus/plugin/StandardPlugin.java
+++ b/src/org/nwapw/abacus/plugin/StandardPlugin.java
@@ -3,6 +3,7 @@ package org.nwapw.abacus.plugin;
 import org.nwapw.abacus.function.Function;
 import org.nwapw.abacus.function.Operator;
 import org.nwapw.abacus.function.OperatorAssociativity;
+import org.nwapw.abacus.function.OperatorType;
 import org.nwapw.abacus.number.NaiveNumber;
 import org.nwapw.abacus.number.NumberInterface;
 
@@ -20,7 +21,7 @@ public class StandardPlugin extends Plugin {
 
     @Override
     public void onEnable() {
-        registerOperator("+", new Operator(OperatorAssociativity.LEFT, 0, new Function() {
+        registerOperator("+", new Operator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 0, new Function() {
             @Override
             protected boolean matchesParams(NumberInterface[] params) {
                 return params.length >= 1;
@@ -36,7 +37,7 @@ public class StandardPlugin extends Plugin {
             }
         }));
 
-        registerOperator("-", new Operator(OperatorAssociativity.LEFT, 0, new Function() {
+        registerOperator("-", new Operator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 0, new Function() {
             @Override
             protected boolean matchesParams(NumberInterface[] params) {
                 return params.length == 2;
@@ -48,7 +49,7 @@ public class StandardPlugin extends Plugin {
             }
         }));
 
-        registerOperator("*", new Operator(OperatorAssociativity.LEFT, 1, new Function() {
+        registerOperator("*", new Operator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX,1, new Function() {
             @Override
             protected boolean matchesParams(NumberInterface[] params) {
                 return params.length >= 1;
@@ -64,7 +65,7 @@ public class StandardPlugin extends Plugin {
             }
         }));
 
-        registerOperator("/", new Operator(OperatorAssociativity.LEFT, 1, new Function() {
+        registerOperator("/", new Operator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX,1, new Function() {
             @Override
             protected boolean matchesParams(NumberInterface[] params) {
                 return params.length == 2;
@@ -76,7 +77,7 @@ public class StandardPlugin extends Plugin {
             }
         }));
 
-        registerOperator("^", new Operator(OperatorAssociativity.RIGHT, 2, new Function() {
+        registerOperator("^", new Operator(OperatorAssociativity.RIGHT, OperatorType.BINARY_INFIX, 2, new Function() {
             @Override
             protected boolean matchesParams(NumberInterface[] params) {
                 return params.length == 2;
diff --git a/src/org/nwapw/abacus/tree/TreeBuilder.java b/src/org/nwapw/abacus/tree/TreeBuilder.java
index 9c57741..520d3e9 100644
--- a/src/org/nwapw/abacus/tree/TreeBuilder.java
+++ b/src/org/nwapw/abacus/tree/TreeBuilder.java
@@ -1,6 +1,7 @@
 package org.nwapw.abacus.tree;
 
 import org.nwapw.abacus.function.OperatorAssociativity;
+import org.nwapw.abacus.function.OperatorType;
 import org.nwapw.abacus.lexing.Lexer;
 import org.nwapw.abacus.lexing.pattern.Match;
 import org.nwapw.abacus.lexing.pattern.Pattern;
@@ -24,6 +25,10 @@ public class TreeBuilder {
      * The map of operator associativity.
      */
     private Map<String, OperatorAssociativity> associativityMap;
+    /**
+     * The map of operator types.
+     */
+    private Map<String, OperatorType> typeMap;
 
     /**
      * Comparator used to sort token types.
@@ -43,6 +48,7 @@ public class TreeBuilder {
         }};
         precedenceMap = new HashMap<>();
         associativityMap = new HashMap<>();
+        typeMap = new HashMap<>();
     }
 
     /**
@@ -59,10 +65,12 @@ public class TreeBuilder {
      * @param precedence the precedence of the operator.
      * @param associativity the associativity of the operator.
      */
-    public void registerOperator(String operator, int precedence, OperatorAssociativity associativity){
+    public void registerOperator(String operator, OperatorAssociativity associativity,
+                                 OperatorType operatorType, int precedence){
         lexer.register(Pattern.sanitize(operator), TokenType.OP);
         precedenceMap.put(operator, precedence);
         associativityMap.put(operator, associativity);
+        typeMap.put(operator, operatorType);
     }
 
     /**
diff --git a/src/org/nwapw/abacus/window/Window.java b/src/org/nwapw/abacus/window/Window.java
index a682e22..0e7a95e 100644
--- a/src/org/nwapw/abacus/window/Window.java
+++ b/src/org/nwapw/abacus/window/Window.java
@@ -269,7 +269,10 @@ public class Window extends JFrame implements PluginListener {
         }
         for(String operator : manager.getAllOperators()){
             Operator operatorObject = manager.operatorFor(operator);
-            builder.registerOperator(operator, operatorObject.getPrecedence(), operatorObject.getAssociativity());
+            builder.registerOperator(operator,
+                    operatorObject.getAssociativity(),
+                    operatorObject.getType(),
+                    operatorObject.getPrecedence());
         }
     }