what is the difference between id and class selector of a css?

mohd arif

respected sir/mam
i need answer for the designing point of view.what is the difference between id and class.i see a lot of css in such there is id in id we define class but we can do its viceversa .so how we can differenciate between id and class selector of css.

3 Replies

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Sandeep Singh Shekhawat14y ago
IDs are the most efficient and pseudo classes and pseudo elements are the least efficient.

http://css-tricks.com/the-difference-between-id-and-class/

http://www.impressivewebs.com/difference-class-id-css/

http://www.vanseodesign.com/css/css-selector-performance/
mohd arif14y ago
respected sir thanks for reply.but i am asking for designing point of view difference.the pattern is to hse a id selector in between we use them class selector.but if i prepare design such a way that in a class selector i use id selector then also it works same.then how we can differenciate css and id.
Veerabhadram Dhodla14y ago
If You define Style with ID then it is Specific to control only. You con't use that Style for other control.
If You define Style with class you can use that style to multiple controls with that class name.

In the below example we have two
tags.

If you define style with ID dropDown1.It will applicable to that specific Div only you con't use that same style to other
.

So if you define style with class as "dropDownMenu". Then you can use that same style to other control also.

class="dropDownMenu" id="dropDown1">

class="dropDownMenu" id="dropDown2">