Skiathos is located in the northern Sporades - a green island of around 60km² renowned for its nearly 70 beaches.
The population of more than 5000 is largely located in the port, Skiathos Town, with the remainder spread out in small settlements along the eastern and southern coasts. A busy road connects the main town with the beach at Koukounaries, and smaller connecting roads head off to the airport, from the settlement of Troulos through to the western coast, and up to a couple of monasteries.
The bus service in summer runs along the main road from early morning through to just past midnight at fairly regular intervals and stops at over 20 different spots along the way. Caiques and sea taxis also offer an opportunity to get to other parts of the island, especially some of the more inaccessible beaches on the north and west coasts.

Skiathos Town sprawls up from two harbours split by a small promontory (the "Bourtzi"). The old harbour is where many of the fishing boats and excursion boats are located, while the new harbour to the east is where the ferries from the mainland arrive and depart.
The Bourtzi is a protected area with some remnants of old Venetian fortifications still visible. It is a popular venue for concerts and other local cultural events during the summer season.
Originally the main settlement on Skiathos was at Kastro up in the hills (chosen as a refuge from raids from the sea) but eventually fell into ruin with the establishment of the Greek state and the present-day Skiathos Town was developed in the late 1820s. The ruined settlement can still be visited as part of a walk or jeep excursion into the hills on the island.
Some of the town has been pedestrianised, especially areas around the main Papadiamantis Street, which are popular for bars, restaurants and shops. This area also turns into a thriving nightlife centre in high season.
Excursions can be made to the other islands in the group from the port area during the day. Walks are possible into the interior - either to some of the less-frequented beaches or to the monasteries dotted around the hills.
The Evangelistria monastery (Moni Evangelistria) is especially renowned amongst Greeks as being the birthplace of the national flag during the war of liberation against Turkish rule.
Visitors may also notice the museum dedicated to Alexandros Papadiamantis, a writer born on the island who gained international fame for his books and short stories and who returned from Athens to Skiathos in his later years.
Some hotels are in the harbourfront area while others are located a little bit further back into the main town. As with the beaches, access to the water often means that this location is slightly more expensive:
Hotel Bourtzi
Hotel Emy
Hotel Filoxenia
Hotel La Piscine
Hotel Meltemi
Hotel Rea
Geof Baldry at SkiathosInfo has created a rambling and vastly informative site about the island. It's old school design, sure, and can be difficult to work out where you are, but it is a motherlode of useful tidbits for those who are considering a break on the island. Geof also rents out his own villa accommodation and runs some property and classified websites about the island.
John Fox over at Foxy's Island Walks covers the walking on Skiathos in a pretty in-depth manner and has an extensive range of photos of beaches and sights on the island. His site is one to bookmark if you are thinking of any kind of walking holiday in the sun, as he covers a variety of other islands as well.
Just to round things out and make it clear, this site isn't (and makes no pretence about being) an official tourist site about Skiathos. You can find a nice new redesigned one here at Skiathos.gr. The site has some good information about history, sights and local customs.
Anyone looking for general information about the Greek islands, as well as some good (and forthright) local details about the beaches and sights on Skiathos, should check out the excellent Greek Island Postcards website from Mike Mason. There is also a very good selection of island photos taken by Peter and Noreen at Images of Greece along with some expert first-hand information about Skiathos.