List Columns vs Site Columns vs Content Type

List & Library Columns

Most Popular and Easy way to create columns. It’s accessible directly from the ribbon and is available on all lists and libraries.
Advantage: Well, it’s easy to create. Within seconds
Disadvantages: It’s easy to create. Yes, The option is right there in front of you in the ribbon and will satisfy the immediate need for a column. However, it doesn’t promote reusability or help leverage what already exist in a parent site. It exists in that list or library once it’s created and that’s it.
A customer once had close to a 100 document libraries in a site. They all had one column that was exactly the same. Now to update they have to update the column in all the document libraries

Site Column

They are columns that we create in a SharePoint site to be available to its’ sub sites.
Advantages: It can be reused by multiple lists and libraries within and a site and its’ sub sites. It also helps by centralizing the configuration of the column in one place which makes it easier to update choices in a choice column for example that are used by multiple lists and libraries.
It allows all sites from a Site Collection to lookup information in a single list like a customers or manufacturers list for example.
Disadvantages: It is not so intuitive to create as the list/library column and you need administrative rights to create it. If overused, it can create a chaos amongst available sub sites. It also requires the administrator to think about his columns and architecture every time he creates one.

Content Type

A Content Type is a reusable, shareable metadata. The base type of a content type could be an existing content type like Item, Document, Folder, Event, Task, Message, Comment, Post.
Content Types are basically a way of grouping Site Columns together into a reusable group that represents some kind of content to us. For example I could group the Site Columns Invoice #, Customer and Related Product together into an “Invoice Content Type”
Example : Announcement List or Task List are basic content type provided by microsoft.
- Content Type, just like Site Columns, it is pushed to all sub sites of the designated site where it was created.
- A Content Type can only exist within a Site Collection, if you want to reuse it in another you will have to recreate it or you can use content type hub.
-  You can attach a workflow to your content type

Advantages : Content Types are necessary to organize reusable content and configurations within SharePoint. Making sure all Invoices have the same metadata and document templates for example. It can inherit from the other content types
Disadvantages : Little bit complex

Example : Suppose i have a document library for each client. one doc library for georgia pacific, one doc lib for infosys and one doc library for Cisco
Now each doc library will contain specific documents like invoice, contract agreement, sales document, etc
Here i can use site columns and it would work for me but the columns wont be tightly integrated or grouped with each document.
So its better if we create a content type for invoice doc, sales doc or contract agreement.

Content Type Hub 

Now as I mentioned earlier content type are available to only with the sites and it's subsites. Now to overcome this we have content type hub.
Content Type Hub is a central location where you can manage and publish your content types – so now web applications can subscribe to this hub and pull down the published content types from the hub

Happy Sharepointing !

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