Ganesh in Hindu Religion treated as First God and He is prayed initially before starting any new venture for finishing the same without any hindrance.
According to Story He is the son of Lord Shiva, once ate well and to control his belly he tied a snack as belt and start dancing. By seeing his fatty body,belly and dance the Incharge of Planet Moon laughed at Him. Angered on his mocking, Lord Ganesh cursed him for decreasing his charm. On his request to forgive, Lord Ganesh forgave him but since the given curse could not got back, Lord offered his diminishing charm as well increasing charm. By this only, we are getting 15 days bright increasing moon and 15 days brightness reduced moon. The fourth day from the full moon day, He declared, as His pleased day and that day of every month is special for Ganesh Pooja. On that day those who suffer from any domestic problem of any kind can pursue fasting and on the evening finish his/her vrat by seeing moon and ate small food(especially without any onion/garlic/non-veg) Normally the vrat dins the intercourse also to be avoided. (Though this is detailed in the formalities ritually, but proved scientifically that the having intercourse on such days will worsen the health as the persons have not eaten on the whole day of such vrat days - consuming onion/garlic/non-veg items are to be avoided as they are inducing the sexual interest and hampering the spiritual interest) Every Ganesh charthurthi the temple persons are conducting Ganesh pooja with performings of Ganapathi Homam, Abhishekam with milk etc., to the Ganesh Idol. This everymonth Chathurthi is considered as 'Shankad Har Chathurthi'. 30.08.2018 is considered as Maha shankad har Chathurthi.
Beesides the chathurthi day, fourth day of Shravan month after No moon day, that is 3th September of this year (13.09.2018) is considered as Ganesh Chathurthi which is special for Ganesh Pooja. On this day, every house got decorated with mango leaves, Special pooja done to the Lord ganesh Idol (made of sand clay),crown flower garland,bermuda grass (dhoorva). This is to denote that the God Ganesh can be worshiped with simplicity. clay is commonly available,crown flower,bermuda grass available plenty on roadsides, As offer to this God is very simple just two banana is enough but in practice we offer on the day of Ganesh pooja with modak made of rice flour and sweet made with coconut and jaggary. Coconut is broken before him is to denote we open our heart to him and shown the white of our heart.
Totally speaking every religion has some meaning of worship and we should honour them without commenting or mocking as they made only for our welfare. If we do not follow by mocking etc., the loss is only to us.