The Torah emphasizes the link between Passover and Shavuot, the very beginning of the redemption from Egypt and its culmination, through the commandment of “Sefirat Ha'omer”. We count the days and weeks from the second day of Passover until the festival of Atzeret, The Day of Assembly, as Shavuot is called in the Torah.
The words “Sefirat Ha'omer” actually mean, "counting of the omer." The “omer” was an offering of newly harvested barley that was brought to the Temple in Jerusalem on the 16th of Nissan, the second day of Passover. In contrast to the Passover barley, the offering on Shavuot was bread made from wheat flour. Barley is often used as animal fodder, while wheat is predominantly for human consumption - and bread is an exclusively human food. Thus, as we count from Passover to Shavuot, we also mark our progression from slavery to our material animal needs, to the increasingly human realm of free will, intellect and attachment to God.
For the Jewish people who came out of Egypt, the period between the Exodus and the Revelation at Mt. Sinai was one of continuous spiritual awakening. Their relationship with God grew stronger and closer. Miraculous events occurred daily. For the Jewish people in subsequent generations, this period continues to be one of the greatest times of the year, in which we prepare ourselves for a renewal of our commitment to the Torah on Shavuot.