The period between Ashad sud ekadashi (2 July 2009) to Kartik sud ekadashi (30 Oct 2009) is referred to as the Chaturmas, literally, 4 months. During this time, all disciples will take extra vows such as fasting, scripture recitals, meditation and other religious observances.
A story is narrated in the Purans about the deity Ekadashi, such named because she emerged from the one of the Lord's indriya. There are 5 gnaan indriya, senses, and 5 karma indriya, the controlling organs of these senses. The mind controls all the organs so is considered the 11th organ. Ekadashi literally means eleven, ek + dash, 1 + 10 = 11. The deity Ekadashi was granted her wish and was allowed by the Lord to reside in his eyes for the duration of the chaturmas. Thus the Lord is said to hibernate during this period. That is why the Ashad sud 11 is also referred to as the Devshayani (dev - Lord, shayan - sleep) ekadashi. During the period that the Lord is resting, disciples will practice extra religious practices (niyams) to please the Lord.
On a practical level, this time period is when the monsoon season falls in India. As a result of the heavy rainfalls, it would be impossible for the wandering sages and preachers to travel the land to preach and offer spiritual guidance. Therefore, during this period they would remain resident at one place. As they are no longer travelling, they have spare time, which is occupied with the extra vows, and thus they further please the Lord.
During these four months we have lot of festivals. Some are religious in nature while others have a social significance and importance-Immediately after the advent of Chaturmas we get the Guru Poornima. Thereafter comes the month of Shravana. This month is full of important days. Shravana Mondays are important for the worship of Lord Shankar. The Poornima in this month is the Narali Poornima which marks the end of heavy rain and the throwing of the coconut in the sea appeases the sea and it calms down.
During this four months Some religious books like Mahabharat, Ramayan, Bhagwat or Vishnu Sahastra could be read everyday according to the time available to everyone. Somebody could undertake to pay a daily visit to a certain temple. Others could take a vow to do "Mantra Jap" of a certain mantra for a certain number of times everyday.