Web designers like to throw around a lot of jargon. So, I want to focus on the more popular techno-babble and try to dispel some of the mystery. First up: semantic code.
What Is Semantic Code?
Even if you are not a web designer, you are probably aware that your site is written in HTML. HTML was originally intended as a means of describing the content of a document, not as a means to make it appear visually pleasing.
Semantic code returns to this original concept and encourages web designers to write code that describes the content rather than how that content should look.
For example, your web designer might have coded the title of your page like this:
<font size="6"> <strong>Article Title</strong> </font>
That would make the title large and bold giving it the appearance of a page title, but there is nothing that describes it as a title in the code. That means a computer is unable to identify this as being the page title.
To write the same title semantically so that a computer understands that this is a title, you would use the following code:
<h1>Article Title</h1>
The appearance of your heading is defined in a separate file called a “cascading style sheet” without interfering with your descriptive (semantic) HTML code.
Why Is Semantic Code Important?
One reason why semantic code is essential is that without explaining what a piece of content is, a computer has no way of knowing. The ability of a machine to understand your content is vital for two main reasons:
-
Many visually impaired people rely on speech browsers to read pages back to
them. These programs cannot interpret pages very well unless the website
clearly explains them. In other words, semantic code aids accessibility
- Search engines need to understand what your content is about to rank you properly on search engines. Therefore, semantic code tends to improve your placement on search engines, as it is easier for them to understand.
However, semantic code has other benefits too:
-
As you can see from the example above, semantic code is shorter and so
downloads faster.
-
Semantic code makes site updates easier because you can apply design
style to headings across an entire site instead of on a per-page
basis.
-
Semantic code is more straightforward for people to understand too, so
if a new web designer picks up the code, they can learn it much
faster.
-
Because semantic code does not contain design elements, it is possible
to change the look and feel of your site without recoding all of the
HTML.
- Once again, because the design is held separately from your content, semantic code allows anybody to add or edit pages without having to have an astute eye for design. You describe the content, and the cascading style sheet defines what that content looks like.
How to Ensure a Site Uses Semantic Code?
Unfortunately, no tool can check for semantic code. It is a matter of
looking at the code and seeing if it refers to colours, fonts or layout
instead of describing what the content is.
If looking at code, all sounds a bit too scary then an excellent place to
start is by asking your web designer if he codes semantically. If he looks
at you blankly or starts waffling, you can be sure he does not.
Difference Between Syntax and Semantics
Syntax and Semantics are very significant terms relating to any programming
language. The syntax in a programming language involves the set of permitted
phrases of a language whereas semantics expresses the associated meaning of
those phrases.
There are some relationships between syntax and semantics where each semantic
element is linked to at least one syntactic rendition and the other one
assures that each syntactic representation has a distinctive meaning.
| BASIS FOR COMPARISON | SYNTAX | SEMANTICS |
|---|---|---|
| Basic | Permitted phrases of a language. | Interpretation of the phrases. |
| Errors | Handled at the compile time. | Confronted at runtime. |
| Relation | Syntactic interpretation must have some distinctive meaning. | Semantic component is associated with a syntactic representation. |
Definition of Semantics
Semantics term in a programming language is used to figure out the
relationship among the syntax and the model of computation. It emphasizes
the interpretation of a program so that the programmer could understand it
in an easy way or predict the outcome of program execution. An approach
known as syntax-directed semantics is used to map syntactical constructs to
the computational model with the help of a function.
The programming language semantics can be described by the various
techniques
– Algebraic semantics, Axiomatic semantics, Operational semantics,
Denotational semantics, and Translation semantics.
-
Algebraic semantics interprets the program by defining an algebra.
-
Axiomatic semantics determine the meaning of a program by building
assertions about an association that detain at each point in the
execution of the program (i.e. implicitly).
-
Operational semantics compares the languages to the abstract machine,
and the program is then evaluated as a sequence of the state
transitions.
-
Denotational semantics expresses the meaning of the program in the form
of a set of functions operating on the program state.
- Translational semantics focuses on the methods used for translating a program into another language.
Definition of Syntax
The Syntax of a programming language is used to signify the structure of
programs without considering their meaning. It basically emphasizes the
structure, layout of a program with their appearance. It involves a
collection of rules which validates the sequence of symbols and instruction
used in a program. The pragmatic and computation model figures these
syntactic components of a programming language. The tools evolved for the
specification of the syntax of the programming languages are regular,
context-free and attribute grammars.
However, what is the use of grammar in this aspect? The Grammars generally
are the rewriting rules whose purpose is to recognize and generate the
programs. Grammar does not rely on the computation model instead used in the
description of the structure of the language. The grammar contains a finite
set of grammatical categories (such as noun phrase, verb phrase, article,
noun, etc), solitary words (elements of the alphabets) and the well-formed
rules to specify the order within which components of the grammatical
categories should appear.
Syntax analysis is a task performed by a compiler which examines whether the
program has a proper associated derivation tree or not.
The syntax of a programming language can be interpreted using the following
formal and informal techniques:
-
Lexical syntax for defining the rules for basic symbols involving
identifiers, literals, punctuators and operators.
-
Concrete syntax specifies the real representation of the programs with
the help of lexical symbols like its alphabet.
- Abstract syntax conveys only the vital program information.
Types of grammars
-
Context-free grammar is prevalently used to figure out the whole
language structure.
-
Regular expressions describe the lexical units (tokens) of a programming
language.
- Attribute grammars specify the context-sensitive part of the language.
Conclusion
The syntax of a programming language is a collection of rules to specify the
structure or form of code whereas semantics refers to the interpretation of
the code or the associated meaning of the symbols, characters or any part of
a program.
