Back end scripting, front end scripting what is the difference between two?

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Client side validation and server side validations

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Which type of validations is better or best? Server side validation or Client side Validation?

Validations can be performed on the server side or on the client side ( web browser). The user input validation take place on the Server Side during a post back session is called Server Side Validation and the user input validation take place on the Client Side (web browser) is called Client Side Validation. Client Side Validation does not require a postback. If the user request requires server resources to validate the user input, you should use Server Side Validation. If the user request does not require any server resources to validate the input, you can use Client Side Validation.

Server Side Validation
In the Server Side Validation, the input submitted by the user is being sent to the server and validated using one of server side scripting languages such as ASP.Net, PHP etc. After the validation process on the Server Side, the feedback is sent back to the client by a new dynamically generated web page. It is better to validate user input on Server Side because you can protect against the malicious users, who can easily bypass your Client Side scripting language and submit dangerous input to the server.
For example, if the user enters an email, you can show an error message after click the button has to check in in the database not immediately so the user can enter unique every field before they submit the form.

Client Side Validation
In the Client Side Validation you can provide a better user experience by responding quickly at the browser level. When you perform a Client Side Validation, all the user inputs validated in the user's browser itself. Client Side validation does not require a round trip to the server, so the network traffic which will help your server perform better. This type of validation is done on the browser side using script languages such as JavaScript, VBScript or HTML5 attributes.
For example, if the user enters an invalid email format, you can show an error message immediately before the user move to the next field, so the user can correct every field before they submit the form.
Mostly the Client Side Validation depends on the JavaScript Language, so if users turn JavaScript off, it can easily bypass and submit dangerous input to the server . So the Client Side Validation cannot protect your application from malicious attacks on your server resources and databases.
As both the validation methods have their own significances, it is recommended that the Server side validation is more SECURE!