In the Web development world, what exactly do backend/server-side programmers do? I guess I don't really understand the whole concept.
I've done the HTML/CSS layouts and website design and a little bit of SQL with PHP (still enhancing my skills, it's more of a side project for me). I've also done a small amount of JavaScript/JQuery.
But I don't understand the "backend" work, such as the scripting languages (Rails/Python/etc) and such. What exactly do you "do" with them?
If you've used PHP, then you've done server-side work!
In layman's terms, client-side code is run on your computer, in your Web browser, and server-side code is run on a computer on the Internet, and the results of the server-side computation are then sent over the Internet to your browser.
When you wrote PHP code that ran SQL statements, the SQL calls were made on the remote computer (the server) and that result -- usually in the form of generated HTML -- is then sent over the Internet to the browser.
JavaScript, on the other hand, is run in your browser. So is CSS.
Check out The Difference Between Client Side and Server Side Programming for more information.
The basic premise is:
The user gives his input, sends it over a network of some kind and the server then does it's magic according to the input.
Basically you want all the security and validation to be performed server-side. With the niceties running client side, like unobtrusive form validation (you still need to validate server side though!).
The big question: Why?
Users can modify information on their machine. As an example see game trainers which modify memory values to let users 'hack' the game. If you do the core things on your machine, on your physical premises, you significantly lower the chances of someone tampering with your security checks.
you design Front end stuff when you design systems that interact with the the client of your systems. Notice here the word client is quite large but basically means you are working on front end when you are providing an interface to the outside world.
Most website are just front end, that is they provide information to the outside world and most times this information can be stored quite simply as text in HTML files.
You design back end when you need to provide services and encapsulate functionality that your front end will consume. This allows to displace some of the workload from the client (front-end) to the server (back-end). You will do this in instances when you need to coordinate information from different clients that could access your system concurrently. Or if you need to use a central data repository to collate dynamic data, or again if you need some specific security requirements. This list is by no means exhaustive, just quick examples.
so to put it short, Front-end (client) will present information to the outside world. Usually these are humans through some sort of GUI either HTML or otherwise.
Back end will provide means to centralize services for your front-end to use. Using a back-end is not mandatory and is adds complexity to a system, but it allows to manage better the complexity inherent to the system you are trying to build.
For example it is possible to provide a service such as a wiki solely through front end but it will have many limitations that using a back-end to store the data and serve it to the front-end would resolve in a more natural fashion.
The front end is the stuff that runs in the browser, the backend such as PHP runs on a server and stores data in the database and does that kind of stuff.
In my opinion server-side work (which it has already been mentioned is anything that runs on the server the website is being accessed from) is what gives a site real life. Much of the functionality can still be achieved using client-side technologies but in my opinion this is a much more complicated approach and much less secure in that clients have access to everything that is in the client-side code. PHP and ASP are in a way hybrid programming languages which are intended almost exclusively to serve webpage content to a browser after doing some computational activities. When you start working with python, ruby, java, or other programming languages you have more power and capabilities but a little more work to send resulting information to the client at the end of the process. In the end it really depends on what you want to do and what languages you're comfortable with as to what you should choose to use.
There are two sides to any typical web app/web site.
Front Side - Which control's the ui/layout/colors/fonts etc
Back Side - Handles manipulation of data in the database, or file manipulation, does lots of logic, if this, do that, if not do this, etc. Integrates with the web server software such as Apache/IIS/etc, and database server software such as mySQL/PostreSQL/MS SQL Server.
The back side is the far more powerful side, because it can do so many things, from creating excel files, generating reports, doing calculations, getting data from different servers.
Then it prepares and displays that data, how the Front Side is setup.
To do well in either is hard work, lots of practice, learning, and self-discipline.
If you want to be the best, practice, and never stop learning, and never assume you know all the answers.
