DFD, it was the first thing made me dig deep. On my early days top-down, bottom up this terms were hibro to me. But diagrams were always so favorite to me. A language which every one can understand. Models/diagrams are set of symbols or i can say a composition to express any thing. It felt to me better than any thing for communication.

DFD-Data Flow Diagram, i amazed how easily it is describing a system. '0' - Level then 1st level then 2nd level ; i wondered its slowly n' slowly digging deep.

Who whatever says to me, after selecting a domain/ System boundary the first step of analysis is :
--Identifying the Stakeholders.
Accounting system like to introduce these stakeholders as external users, in general they are the interested parties. Normally for a sales domain customer, dealer, supplier, bank, Govt. , public , prospective customers, owners, prospective owner, other investors all are counted as Stakeholders.
Now a question may arise why the Stakeholders comes at the beginning. Its easy as a business never deals without interest. So always interested parties/ stakeholders are its concern.
Now you may say what is this concern? So easy, system processes act on inputs and outputs; now look without these stakeholder there is no one to give inputs and get outputs.

You can go through the below links to have some idea
http://www.methodsandtools.com/archive/archive.php?id=48
http://www.jisc.ac.uk/fundingopportunities/proj_manguide/projectplanning...
http://www.bized.co.uk/educators/level2/busactivity/lesson/knowing1.htm

to be continue...