UrlEncode - why and when to use this?

Hello,

I'm trying to understand more about when and why we should use URLEncode for asp.net.  Currently I don't use it anywhere in my DetailView.  Basically, anytime I request information from the users, I have a DetailView control where they input the information, along with validation controls to verify content/busines rules.  Once they submit it, the row is inserted into the db. 

1)  Should URLEncode be used anytime you gather data from a user? 

2) When should it (or should not) be used? 

3)  Is the general idea behind URLEncode to allow your application to accept special characters ' & / <>, but in a safe way b/c we're encoding them.

4)  Is the actual string stored with the hexadecimal charactes in the db...thus you have to decode if you're displaying the data from the db?

Thanks!
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