Understanding Salesforce URL

Following is the information on the URL structure in Salesforce. I have copied the information as it is from the following 2 posts 
1st post is by Mike Schinkel and second post is by Alessandro
http://thoughtsonsalesforce.com/blog/salesforce/crm/url-structure http://salesforce.phollaio.com/2007/01/11/salesforces_url_structure/

Thanks guys for putting this post, it helped a lot. 

Instances
Salesforce’s organizations reside on multiple instances, to find out what instance you’re on, once you logged into Salesforce, have a look at the address bar; you’ll notice the URL starts with something like:

ssl – North America #0 (aka na0)
na1 – North America #1
na2 – North America #2
na3 – North America #3
na4 – North America #4
na5 – North America #5
emea – Europe, Middle East, Africa
ap – Asia, Pacific
tapp0 – Sandbox #0
tapp1 – Sandbox #1

https://xyz.salesforce.com

where xyz is the name of the instance your organization is on.

Objects’ specific URLs

Every Salesforce’s object has it’s specific URL, here are listed the links to the standard objects:

Objects	URLs	Objects’ code
Accounts	https://[instance].salesforce.com/001/o	001
Contacts	https://[instance].salesforce.com/003/o	003
Leads	https://[instance].salesforce.com/00Q/o	00Q
Cases	https://[instance].salesforce.com/500/o	500
Solutions	https://[instance].salesforce.com/501/o	501
Reports	https://[instance].salesforce.com/00O/o	00O
Opportunities	https://[instance].salesforce.com/006/o	006
Campaigns	https://[instance].salesforce.com/701/o	701
Products	https://[instance].salesforce.com/01t/o	01t

Basic action URLs

Use the following URLs to perform the listed operations on a specific object. Note this is fundamental to then understand how to create internal custom links.

Object’s overview page
https://[instance].salesforce.com/[object]/o
ie: https://emea.salesforce.com/500/o

Create a new record
https://[instance].salesforce.com/[object]/e?retURL=/[object_code]/o
ie: https://emea.salesforce.com/500/e?retURL=/500/o

Edit a record
https://[instance].salesforce.com/[object]/[recordID]/e?retURL=[recordID]
ie: https://emea.salesforce.com/50020000000chRD/e?retURL=/50020000000chRD

Clone a record
https://[instance].salesforce.com/[object]/[recordID]/e?retURL=[recordID]&clone=1

Delete a record
https://[instance].salesforce.com/setup/own/deleteredirect.jsp?delID=[recordID]

where:

• [instance] is the instance’s name your organization resides on;
• [object] is the object’s code;
• [recordID] is the ID of the record itself.