Understanding the SharePoint Hierarchy

One of the most con­fus­ing sub­jects for me to grasp early on was under­stand­ing the Share­Point hier­ar­chy. I couldn’t tell a web appli­ca­tion from a site col­lec­tion. It con­fused me to no end. Well, after much study it seems rather sim­ple now! Here’s a dia­gram with a short explanation.

At the top of the hier­ar­chy are server farms. This encom­passes all the phys­i­cal servers that com­prise your SP instal­la­tion. It may con­sist of one server or twenty. When you run the SP con­fig­u­ra­tion wiz­ard after installing MOSS/WSS you either cre­ate a new server farm or con­nect to an exist­ing one. It’s done once.

Once you have your server farm you must set up a web appli­ca­tion. This is what cre­ates a cor­re­spond­ing web­site in IIS to host the site. This is where it gets its appli­ca­tion pool and other IIS prop­er­ties. You can cre­ate mul­ti­ple web appli­ca­tions on a server farm.

Now you have a hol­low web appli­ca­tion but no SP sites. Enter site col­lec­tions. It is sim­ply a col­lec­tion of Share­Point sites inside the web appli­ca­tion. Here you define a top-level site. You can have mul­ti­ple site collections.

From your site col­lec­tion you have a top-level site that will have mul­ti­ple sites under­neath it. This is the com­mon SP inter­face seen by end users.

And finally we have the con­tent inside the sites. This includes (but not lim­ited to) lists, libraries, web parts, etc.

It’s worth men­tion­ing that Shared Ser­vice Providers (MySite, Excel Ser­vices, BDC) in MOSS are at the web appli­ca­tion level and are for all site col­lec­tions under­neath it. You can, how­ever, have dif­fer­ent Shared Ser­vice Providers for indi­vid­ual web applications.