SAP Basics Feature

Configuration of the SAP modules
Transaction SPRO - this is the main tree for all the configuration.
Function Key
F1 - Help
F4 - Possible entries or matchcode for the field you are accessing
F5 - Selection screen
F7 - Previous screen
F8 - Next screen
F9 - Technical info
CTRL+X - Cut
CTRL+C - Copy
CTRL+V - Paste
Navigation
/n           Skip to the next record if you are processing one batch input  session
/bend     Cancel a batch input foreground process
/nend     Close all R/3 sessions and logoff
/nxxx x   Call the transaction xxxx in the same session
/o           Generate a session list
/oxxx x   Call the transaction xxxx in an additional session
/i             Delete the current session
/h            Turn the debug mode on
/$tab       Reset all buffers (for System Administrators)
/$syn c    Synchronize instances buffers (for System  Administrators)

In 4.x,  you can have long SAP transaction code up to a maximum of 20 character
What is the difference between configuration and customisation?
In a nut shell, customization is done when the client's requirement cannot be mapped with SAP standards. Here you will have to take the help of ABAPers to develop the programs/change the program codes in order to match the clients business requirements

Configuration is done with out any developed programs