Server side and client side validations..
Client Side Validations
Its quick… its fast… but it has its own limitations…
Or I may disable the scripts in my browser and yes it is also true that all browsers do not support scripting… so at that time the code written for the validation is nullified. A user can enter any thing he wants and can produce some internal application error… or can corrupt ur database.
Just think that what can spammers do if the image verification is validated at the client side…
Now lets go to server side validations….
Server Side Validations
Slow…. takes time… but are reliable…. a user can access my web application from PDA or any browser… It may or may not support scripting…. I am safe as the logic resides in my server… So i get protection against spammers, logical errors, application errors which can come due to inconsistent data..
On the other hand it is more easier to write validations in any Programming language and to maintain it. It takes lesser time.
Hope this will give you a better understanding of what the reality is in todays unsafe world.