Back to Square One: Learning from Scratch

So what is a signal?
Anything that holds information is a signal.


How's it represented?
As a mathematical function of  more than one variable one of which is time.


Now in the Matlab context:
Let's first define a time axis 
>>t = (0: 0.01 :pi);
>>y=sin(t); %% So we have the y array with sine values for all values of t array.Good!
>>plot(y);