Core programming fundamentals · Lesson 2 of 60 · Concept lesson · Optional

Syntax and semantics

Syntax is the set of rules for how code must be written, like the grammar of a sentence.

Semantics is what the code means, which is what it actually does when it runs.

Code can follow the syntax perfectly and still do the wrong thing.

Picture it

syntax error:
  print("Hi"
  (a bracket is missing, so the
   code cannot even be read)

semantic mistake:
  4 + 6 / 2
  (readable, but it means 4 + 3,
   not (4 + 6) / 2)

Two different kinds of mistake. A syntax error breaks the grammar, so the computer cannot read the line. A semantic mistake is readable code that means something other than what you intended.

Code example

console.log(4 + 6 / 2);
console.log((4 + 6) / 2);

Output:

7
5

Both lines are valid syntax. They print 7 and 5, because the brackets change the meaning.

print(4 + 6 / 2)
print((4 + 6) / 2)

Output:

7.0
5.0

Both lines are valid syntax. They print 7.0 and 5.0, because the brackets change the meaning.

Check yourself

Pick an answer for each question. You can retry as many times as you like.

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Core programming fundamentals · Lesson 2 of 60 · Concept lesson · Optional

Syntax and semantics

Syntax is the set of rules for how code must be written, like the grammar of a sentence.

Semantics is what the code means, which is what it actually does when it runs.

Code can follow the syntax perfectly and still do the wrong thing.

Picture it

syntax error:
  print("Hi"
  (a bracket is missing, so the
   code cannot even be read)

semantic mistake:
  4 + 6 / 2
  (readable, but it means 4 + 3,
   not (4 + 6) / 2)

Two different kinds of mistake. A syntax error breaks the grammar, so the computer cannot read the line. A semantic mistake is readable code that means something other than what you intended.

Code example

console.log(4 + 6 / 2);
console.log((4 + 6) / 2);

Output:

7
5

Both lines are valid syntax. They print 7 and 5, because the brackets change the meaning.

print(4 + 6 / 2)
print((4 + 6) / 2)

Output:

7.0
5.0

Both lines are valid syntax. They print 7.0 and 5.0, because the brackets change the meaning.

Check yourself

Pick an answer for each question. You can retry as many times as you like.

Loading the questions…