Names of many places/cities end with "bad" such as Hyderabad, Ahmadabad, Secunderabad, etc. Is there any special meaning for "bad"? Please put some light on 'pur' suffix in India too.

The suffix is not "bad", it is "abad" as in Hyderabad, Ahmedabad, Secunderabad, Allahabad etc. The meaning of "abad" in Urdu is "The area or environment where an organism or ecological community normally lives with reference to the name". You can relate to the fact that these cities were ruled by Muslim rulers in recent past or maybe dominant Muslim population(using Urdu for daily use) and it is where the influence of Urdu comes in. You can find similar suffixes in cities like Bharatpur, Jaipur and many more where Hindi is widely spoken and pur in Hindi means "city" or "settlement".

Excellent answer by Amandeep. I had asked this question to myself sometime when I was 12~ and I explained this to myself in the following way: Abadi in Urdu means population or people. So, Hyderabad would mean 'Hyder ki Abadi' meaning 'The people of Hyder'. Secunderabad would mean 'Sikandar ki Abadi' meaning 'The people of Sikander'. Allahabad would mean 'Allah ki Abadi' meaning 'The people of Allah'. And so on...

Adding on to Aditya and Amandeep's answer. Abad also means to prosper (the opposite being barbad). So the names of cities are actually a play on the word abad as well. Thus Allahabad means both "Allah's population" and also "May Allah prosper".

Muslim Rulers in India changed the names of indian cities on their name or in the name of allah. Allahabad( http://en.wikipedia.org/wiki/Mughal_empire emperor http://en.wikipedia.org/wiki/Akbar renamed Prayag as Allahabad) , moradabad( Rustam Nagar. Later on it was named as Moradabad after http://en.wikipedia.org/wiki/Shah_Jahan's son http://en.wikipedia.org/wiki/Murad_Baksh), ghaziabad( Ghazi-ud-din, who called it Ghaziuddinnagar initially), hyderabad(there r many stories behind this name) , n many more. Their respective wikipedia pages contains all this information

Well my hometown in ALLAHABAD which was named as Allah(God in Urdu) Abad(Urdu).  It is one of the common things to use in india. Few more e.g Halli in bangalore most of the places will use Halli that means village.Devanahalli - Where BIAL is situated can be one of the e.g.