Sikkim, Nepali: सिक्किम, is a state in East India in the Himalayan foot hills also bordering China (Tibet), Nepal and Bhutan.The name has been coined from the words 'Su','Him'i.e. beautiful home.Though it should be better named by abode of nature.The snow covered mountains & lush green valleys not only invigorates one's soul,it also leaves the spectators bewildered by the extravaganza of its natural beauty. Nearly 40% of the total area is forested.
The state official language of Sikkim is Nepali, which is also the primary language of most locals. Many other languages such as Dzongkha and Tibetan are also spoken by smaller numbers. However, Hindi is also widely spoken as a second language, and all educated people are able to speak English.
As of March 2012, it is still necessary to obtain a Restricted Area Permit (also known as Inner Line Permit) for foreigners to travel in Sikkim. The permit is a piece of paper containing your passport data and dates you are permitted to travel (typically, 15 days). When entering and exiting Sikkim, your passport will be stamped much in the same manner as when crossing state borders. Obtaining a permit is a pure bureaucratic formality and usually takes a few minutes. You will need to fill in an application form and provide a few passport photos (1 and 2 have been reported).
The permit can be obtained when crossing the Sikkim state border by road in Rangpo or Meili. It is also available from Sikkim travel desk in Darjeeling located inside the Old Bellevue Hotel (opposite to Glenary's restaurant in Chowrasta district), and from Sikkim Tourism Center in Siliguri located at the S.N.T. bus stand (the place from which government buses depart for Sikkim, S.N.T. means "Sikkim Nationalized Transport") in the vicinity of Siliguri Junction railway station (different from New Jalpaiguri station, and can be reached from there by taxi/public shared taxi), the area is known as Pradhan Nagar. The web-site of Ministry of Home affairs states that permits can also be obtained at large international airports (Delhi, Mumbai, Chennai, Kolkata), but locating the relevant facilities proved difficult due to incompetence of the personnel. Permits can also be applied for at the time of Indian visa application, or at 14 Panchsheel Marg, New Delhi 110021 (011 26115346) and 4/1 Middleton Street, Kolkata 700071 (033 22817905)
Nearest airport for Sikkim is Bagdogra, near Siliguri in North Bengal, which is 124 km and approximately four hours drive from Gangtok. Indian Airlines, Jet Airways, SpiceJet, Go Air etc. service Bagdogra linking it with other major airport in India (including Guwahati). Druk Air flys twice weekly from Bangkok, stopping in Bagdogra before continuing to Paro in Bhutan. You can also take a helicopter from Bagdogra to Gangtok.
Construction of a 50-km rail link from Sevoke, West Bengal to Rangpo, Sikkim started in 2009, but is not expected to be ready until 2015, and it'll take another few years until it reaches another 40 km to Gangtok.
Meanwhile, the nearest railway stations are Siliguri and New Jalpaiguri. Both of these have a number of trains connecting them to Kolkata. You should be able to get pre-paid taxis to Gangtok outside the railway stations easily.
Rumtek Monastery – 24 km from Gangtok in East Sikkim – the main seat of the Karma Kagyu school of Tibetan Buddhism in Sikkim. Originally built by the 9th Karmapa Wangchuk Dorje in 1740, but fell into disrepair. The current structure dates from 1959.
Tsongmo Lake – 40 km from Gangtok in East Sikkim on Nathula route – Tsongmo Lake (also called Changu Lake or Tsomgo Lake) is a large lake in the East Sikkim district of India. It is oval-shaped, with a length of about one kilometre and has an average depth of fifteen metres.It is also a home of Brahminy Ducks besides being a stopover for various migratory birds. Etymologically "Tso" means lake and "Mgo" means head, thus literally meaning "source of the lake" in the Bhutia language. Tsongmo lake is declared a sacred lake by the local Buddhist and Hindu population. The lake remains hidden in the rich forest cover. It is believed that the birds do not permit even a single leaf to float on the lake surface. There is a motorable road from Pemayangtse right up to the lake area. It falls in the restricted area and hence an inner line permit is required by Indians to visit this place. Foreign nationals are not permitted to visit this lake without special permission. A little distance from the lake is a beautiful natural three storied cave, the Tseten Tashi Cave is a worth to visit.
Nathu la pass - The Nathu la pass lies on the Indo-Chinese border and is only open for Indian tourists. People who wish to visit Nathu la should get special permission one day in advance. Please note, however, that the pass is not open on Mondays & Tuesdays every week.It closes in the winter and opens in May.
Baba mandir - Eight kilometers from Nathu la pass is the original Harbajan Singh Baba Temple from which the Indo-Bhutan border is approximately 6 km and the India-China border is around 5 km. A must visit place for all those who like to explore places!
Kabi Lungstok - Kabi Lungtsok is a historic place, located on North Sikkim Highway, 17 km away from Gangtok. This is the same place where the historic treaty between Lepcha Chief Te-Kung-Tek and the Bhutia Chief Khey-Bum-Sar was signed ritually.
Chungthang - Chungthang is in the northern part of Sikkim. It is located at the confluence of Lachen and Lachung Chu and is the starting point of the river teesta. It is believed that Chungthang is blessed by a guru Rimpoche.
Gurudongmar Lake- Gurudongmar lake is at an altitude of 5150 meters ft. The lake is both sacred and pristine. It has crystal clear waters and and the way leading to it is a cold desert. The lake remains completely frozen during the Winters, except for a small part which is considered to be touched by Guru Padmasambhava. Visits to the lake are allowed after obtaining a permit from the Government. Foreign nationals are not allowed to go there. The whole area is controlled by Army, due to it's proximity to China. . The air pressure is only 55 % compared to sea level , making altitude sickness a certain outcome for any longer stay without lengthy acclimatization. For day trip visitors a night halt at Lachen is advised for minimal altitude acclimatization . It is advisable to not to run or speak loudly. Just sit by the lake enjoying it's beauty and the surrounding mountains. Tourists are generally asked to leave the place by 1 - 2PM, after which the wind speeds picks up and is enough to carry small stones with it!
Dzongri trek: Dzongri trek is possible in the west part of the Sikkim. This trek is suitable for those trekkers who wish to go for a short and easy trek. This trek provides beautiful view of unique landscape, which permanently gets printed on the trekkers mind. 
You must eat delicious momos stuffed with meat (also known as 'Dumpling'). For vegetarians, veg momos are also available along with Thukpas (noodle soup). Phagshapa is a strip of pork fat stewed with radishes and dried chillies.