I have recently started going through sound card drivers in Linux[ALSA].
Can a link or reference be suggested where I can get good basics of Audio like :
Sampling rate,bit size etc.
I want to know exactly how samples are stored in Audio files on a computer and reverse of this which is how samples(numbers) are played back.
The Audacity tutorial is a good place to start. Another introduction that covers similar ground. The PureData tutorial at flossmanuals is also a good starting point. Wikipedia is a good source once you have the basics down.
Audio is input into a computer via an analog-to-digital converter (ADC). Digital audio is output via a digital-to-analog converter (DAC).
Sample rate is the number of times per second at which the analog signal is measured and stored digitally. You can think of the sample rate as the time resolution of an audio signal. Bit size is the number of bits used to store each sample. You can think of it as analogous to the color depth of an image pixel.
David Cottle's SuperCollider book also has a great introduction to digital audio.