What is sandbox solution in SharePoint?Please explain

Sandbox solution is a new feature in sharepoint 2010. As sharepoint is a server component, so instead of giving full access on farm to a site collection administration sandbox will give a limited access of the developed code.

In SharePoint 2007 only a farm administrator can deploy or install solutions to SharePoint site. But in SharePoint 2010 a user with site collection administrator permission itself can deploy the solutions. This feature of SharePoint 2010 reduces the dependency on farm administrator. A sandbox solution is a custom code solution which runs in a different sandbox. You can say that sandbox solutions run in a different process while others run in respective SharePoint process.
Why sandbox was introduced by SharePoint?
Now a question may arise that why a SharePoint developer need sandbox solutions or what is the purpose of sandbox solution.
The reason for it is this is pretty simple to do some code in visual studio and deploy it in SharePoint site, of course if you have appropriate permission. So there may be chances where some code may affect SharePoint server performance. So to overcome these situations sandbox solution has been introduced in SharePoint.
How to debug the sandbox solutions:
To debug the sandbox solution you need to attach SPUCWorkerProcess.exe manually from debug menu.
How to manage sandbox solutions
As you know that sandbox solutions works at site collection level.
So to manage sandbox solutions use below steps:
From site actions, select site settings.
Then go to Top level site settings.
Click on solution link from the gallery.
 There are various configuration options in sandbox solutions such as configuring quota for resource.
Few important facts about Sandbox solutions:
Code executes in sandbox are deployed by a Site Collection Administrator.
They are stored in a gallery called solution gallery.
Site collection administrator have limited set of permissions and functionality.
It is executed in a partial trusted environment.
Each solution is isolated to its site collection.
Sandbox solution can be run in Local mode or in Remote mode (executed on dedicated server where SharePoint is installed).
Sandbox solution Life Cycle:

  • Installation: Upload to gallery.
  • Activation
  • Deactivation
  • Deletion