Brief description of indicator :
Indicator
The main variables for the mathematical expression of an indicator are opening price, closing price, highest price, lowest price, all measured at a specific time frame. Volume is also being widely used. There are other minor variables used in some indicators.
If you are able to correlate the variables ( probably with some mathematical differentiation, integration, constants, coefficient, ... etc. ) and produce a prospective display to indicate the price movement, you make your own indicator.
There are over one hundred indicators developed by different people just to indicate the price movement.
Candlestick and bar charts are the most basis/raw form of indicator, which directly display price without going through mathematical calculation.
If anybody agree with me:
Price itself is the perfect indicator.