Ramadhan is the 9th Month in the Islamic Lunar calendar most meritous month of the whole year

Philosophy of Ramadhan
The Holy Quran has told us that the basic objective for which man is created by Allah is that he "worships" Him :
And I did not create Jinn and human beings except that they should worship Me.
The word used by the Holy Quran for the worship is "Ibadah", which has a much wider sense than "worship".

The month of Ramadhan has been designed to maintain a balance between material and spiritual aspects of the human life. This month is meant to maximize the direct acts of ibadah and to maximize the pure mundane activities, so that one may accelerate his spiritual progress to make up the distance and to repair the spiritual loss one may have suffered through his deep involvement in the mundane activities during the year. The days of Ramadhan are designed to keep fast which is an act of ibadah for the whole day, and depriving oneself from any material food for many hours, it lessens the bad spiritual effects, if any, of the material pleasures. The nights of Ramadhan, on the other hand, are spent in offering Tarawih and waking up for tahajjud and suhoor, reducing the time of one's sleep much less than in the normal days. The rewards of the virtuous acts in this month has been multiplied, to encourage the Muslims to the maximum possible acts of ibaadah.

Merits of Ramadhan
It contains a night far better than one thousand months (Laila tul Qadr).

It is a month where Allah has made it obligatory to fast.

It is commendable to stand up praying in its nights.

An optional act of worship (nafl) in this month has the same reward as an obligatory worship (fard) in other days.

Performing an obligatory (fard) act of worship will carry as much reward as the reward of performing seventy obligatory acts of worship in other days.

It is a month of patience and the reward of patience is Jannah (paradise).

It is a month of sympathy.

A month in which the provision for a believer is increased.

If someone provides another person with food to make Iftar, it will cause forgiveness to his sins and freeing his neck from hell and he will be awarded the same thawab as the fasting person will be rewarded for his fast, without decreasing his own thawab.

The first part of this month is mercy from Allah.

The middle part of this month is forgiveness from Allah.

The last part of this month is liberation from hell.

In this month, you should do four acts frequently :
bear witness that there is no God but Allah
seek forgiveness from Allah
pray to Allah to give you the Jannah
seek refuge to Allah from the Fire.

It is a month of divine blessing.

It is a month of purification, to purify one's soul and heart.

It is an opportunity to strengthen one's Imaan.

Show Allah the best of deeds from your side, because unfortunate is the person who deprives himself from Allah's mercy in this month.

Characteristic honours for Muslims in Ramadhan
The smell coming out from the mouth of a fasting person is better with Allah than the smell of musk.
Fish (in the water) keep praying to Allah to forgive the fasting persons until they make Iftar.
Every day, Allah decorates the Jannah and addresses it saying 'It is not too far that my righteous servants shall throw away the burdens (of the worldly life) and shall proceed towards you .
Rebellious satans are shackled in this month.
In the last night of this month, the fasting persons are granted amnesty.

How to Spend Ramadhan
Among other things, one should carry out the following with due care :
To offer every prayer with Jamaah in a mosque.
To rise up a little earlier than the exact time of Suhoor and offer the salah of Tahajjud.
To offer the nafl prayers of Ishraq, Duha and Awwabin.
Recitation of Holy Quran should be done as much as possible.
Dhikr or Tasbeeh, throughout the day.
Prayers and supplications - as much as one can.
A Muslim should give as much money in Sadaqah (charity) as he can afford.

What should be avoided in Ramadhan
Although the sinful acts are totallly prohibited in Shariah, whether in Ramadhan or at any other time, but their prohibition becomes even more severe in this month. If a Muslim continues to commit sins in Ramadhan, it will be a mockery to avoid lawful things and yet be engaged in unlawful acts never allowed in Shariah.
Specially the following acts should be avoided totally:
1. Telling a lie.
2. Backbiting
3. Quarrelling
4. Eating unlawful things
5. Earning through unlawful means.
6. Any act which may harm a person without a valid cause.
In short, one should try his best to refrain from all kinds of sins, and protect his eyes, ears, tongue and all other organs from indulging in an unlawful activity.

Rules of fasting
"Fast" means "to refrain from eating, drinking and having sexual intercourse throughout the day, right from the break of dawn upto sunset, with a clear intention of seeking the pleasure of Allah". It is necessary that there should be an intention which is callled the "Niyyah".

Acts nullifying the fast
Acts nullifying the fast are of two kinds :
1. Acts which make one liable to both qada and kaffara, namely :
(a) Eating something
(b) Drinking something
(c) Having sexual intercourse.
These three acts are liable to kaffarah when they are committed deliberately after one has started a fast, provided that the person committing them knows that they render the fast broken.
In such cases, both qada and kaffarah are obligatory on him. Qada means to keep another fast in lieu of the broken one. And kaffarah means to perform an act to expiate the sin of having broken the fast.
Kaffarah may be given in the following three ways :
(a) freeing a slave
(b) fasting for two months constantly without a break
(c) giving food to sixty persons

2. Acts which do not make the relevant person liable to kaffarah (only Qada is obligatory) :
(a) Eating or drinking unintentionally.
(b) Dropping medicine or anything else in the nose and ear.
(c) Smoking
(d) Emission of semen while touching, kissing or caressing a woman.
(e) Eating or drinking under the wrong impression that dawn has not yet broken, or the sun has set, while otherwise was true.

Acts rendering the fast makrooh
(a) Chewing something or tasting it with the tongue without eating it.
(b) Using tooth paste or tooth powder. However, cleaning teeth with a miswak or a brush is allowed.
(c) Remainig in the state of Janabah (major impurity) for the whole day.
(d) Giving blood to anyone.
(e) Quarelling with someone or abusing him.
(f) Gheebah i.e. to abuse or to blame someone in his absence.
(g) Telling a lie.

Acts which are allowed
(a) Cleaning teeth using a miswak or a brush and ear with cotton swabs
(b) Applying oil or henna to hair
(c) Using eye-drops or kohl (surma/kajal).
(d) Wearing perfume
(e) Taking a shower
(f) Vomiting unintentionally
(g) Entrance of smoke or dust into the throat unintentionally
(h) Ejaculation while dreaming
(i) Delaying the ghusl of janabah upto sunrise.

Suhoor (Sehri)
Suhoor is the meal one takes in the last hours of the night before commencement of a fast. It is a sunnah to have Suhoor. If someone has no appetite at that time, it is advisable for him to have something light. Even by having a few sips of water the sunnah of suhoor can be fulfilled.

Iftar
Iftar means to conclude a fast after sunset by eating or drinking something. It is also sunnah to make iftar soon after sunset, and it is makrooh to delay Iftar after sunset without a valid excuse. However, if someone is doubtful if the sun has set or not, he should not make iftar until he is sure about it, because if it proved at any time that he made iftar even half a minute earlier than the sunset actually took place on his horizon, his fast will be renderred nullified and void.


Tarawih
Another important feature of the month of Ramadhan is Tarawih. It is a special salah (prayer) consisting of 20 rakat which is performed immediately after Isha prayer. This Salah is Sunna Mu`akkadah (repeatedly emphasized) and should not be missed. It is sunnah to complete the recitation of the whole QUran in Tarawih in Ramadhan.

LailatulQadr
One of the most meritous aspects of the month of Ramdhan is that it contains LailatulQadr, the most blessed night of the year. It is a night better than a thousand months. The authentic traditons mention that, in this night, Allah Almighty directs His special mercy towards the people of the Earth, accepts the supplications made by His slaves and forgives a large number of people who repent and pray. LailatulQadr falls in one of the last five odd nights of Ramadhan i.e. 21st, 23rd, 25th, 27th and 29th. The purpose of this alternation is that one should spend all five nights in worship and prayers, so that he may find lailatulqadr with certainty.
No special form of worship is prescribed in this night. The night should be spent by offering as many nafl prayers as one can offer, in recitation of the Holy Quran, in dhikr and Tasbeeh, in supplications and in making sadaqah (charity).
The follwoing Dua can be recited in this night :
Allahumma innaka `afuwwan tuhibbul `afwa f`afu `anni
Allah, You are surely most forgiving and You like forgiving, so forgive me.


I`tikaf
Another unique form of worship in this month is i`tikaf, in which a person gives up all his activities, abondons his attachments, associations and routines and enters the mosque for a specific period. In i`tikafd onre leaves his home and family and undertakes to remain in the mosque for a limited period. It has been declared as Sunnah in the last ten days o f Ramadhan, because Ramdhan is the most suitable time to carry out this worship.

Extracted from the book : Islamic Months (by Mufti Muhammad Taqi Usmani).