I am new to SSL programming and finding some difficulties in understanding SSL concepts. I tried to get it through openssl site,but it is not much informative. Here is my doubts. What is difference between SSL Buffer and BIO buffer..? I mean layerwise detail will be very helpful. Can I use SSL_Write and SSL_Read without setting any BIO object to SSL object..? What exactly BIO_flush will do... I mean is it going to flush all the data to network buffer from BIO buffer.. ? If it is possible to do write and read data from SSL directly without using any BIO object then is it possible to flush the data from SSL buffer to network buffer by any means.. ? It would be very helpful if any body explain these things or giving any links where I can find answers to my questions.