Although Colmar was French for most of its modern history (as all of Alsace and also Lorraine), its population used to be predominantly German. Alsace changed nationalities many times in the course of history between France and Germany. During WWII Hitler reclaimed Alsace (it was annexed to France after Germany lost WWI) and it is quite shocking to see photographs from the time with Nazi flags hanging through the streets. Cultural suppression of local culture led to the Francification of Alsace (and Colmar with it). Notwithstanding, you will still hear a lot of German spoken in Colmar, some because of the numerous tourists from neighbouring Germany and Switzerland, but some spoken by native Alsacians, speaking their German dialect called Alsatian. Alsatian is the local minority language, although it is endangered, with ever fewer speakers in young generations. Alsatian is not identical with standard German, but it is to a certain extent mutually intelligible. In some parts of the city, as well as in Strasbourg, streetsigns will be written in French and Alsatian German underneath. Among the minority languages of France, Alsacian German is the most prosperous one nowadays (followed by Breton, Occitan, Basque and Catalan), and many Alsatians will be delighted to be addressed in German rather than in French (though not all of them). If you do not speak French, German will always be the next preference. English is unfortunately not widely spoken, however if you politely address someone in French they may make an effort to help you despite language barriers.
Colmar lies between Basel (French: Bâle) and Strasbourg. There is a direct train connection from both cities. Be sure to sit on the right side of the train to enjoy the wonderful views of the Vosges Mountains if coming from Strasbourg. If you arrive from the German side, there is a bus leaving near the border at Breisach (to which there is a direct train from Freiburg). The bus-stop is located directly in front of Breisach train station. If you are visiting from Freiburg, it is cheaper to get a RegioElsassTicket, as it is valid for this bus, as well as the entire RVF (Regio-Verkehrsverbundes Freiburg) network.
If you arrive by plane you will probably use one of the closest airports: Euroairport at Basel (with a variety of low cost flights) or Strasbourg (with none). Other airports in the area are Baden Airport, Stuttgart and Zurich.
All of Colmar's attractions are concentrated in its old town. For a medieval city, it is surprisingly big, but you can nonetheless get around on foot with no difficulty.
Please note that there is no luggage storage in the train station, nor anywhere else in town according to the Colmar Tourist Bureau.
There are reasonably good bus links  to many areas of interest, costing €1.40 (2018) each way.
Colmar's old town is the main attraction if you come to Colmar. It is stunningly beautiful and well preserved. You should allow yourself a day to stroll along Colmar's old streets and many many shops.
Wandering about Colmar's old streets is the best way to explore it. There is a variety of shops of different sorts. The Alsatian cuisine is also omnipresent (in restaurants as well as specialist stores). Take a boat trip on the canal from Little Venice.
Most recommended is to buy clothes and shoes in Colmar. The variety is satisfactory and the prices lower than in neighbouring Germany, Switzerland and even Strasbourg. Apart from these, you can find typical crafts which can be bought as souvenirs. Notable is the typical Alsatian pottery. It comes in a coloured variety, usually blue, green or cream coloured, and decorated with motifs of storks (the regional bird) and flowers. Pottery is also available in a pale blue style, but this type has a stronger German influence. Typical wine glasses for the region are short glasses with green stems. Look for tablecloths, tinware and other such households reproduced with depictions of children and adults in typical Alsatian dress. Food and wine are also major components of the Alsatian production, so look below for relevant tips.
Alsace is known for its pastries. Kugelhopf is a well-known cake similar in shape to the American Bundt cake and has raisins with powdered sugar on top. You can buy traditional ceramic Kugelhopf pans in any tourist shop with recipes to make at home. During Easter, small cakes molding from lamb-shaped pans are made. They are served with a ribbon around their necks and topped generously with powdered sugar. Macarons are also found in specialty sweet shops and also in the frozen aisle of the supermarket (try the Monoprix in the center of the town), which can be eaten straight from the box frozen. Note that they are not like American macaroons (coconut haystacks) but are the French version composed of two small, pastel colored cookies made from almond flour (which has a melt-in-your-mouth quality) with an icing in between. In sweet shop you will also find Meringues, made from whipped egg whites and sugar, dyed in pastel colours and then baked. Make sure to try the tarte aux poires, which is a pear tart with an eggy custard filling with baked pears.
Tarte flambée (Flammekueche in Alsatian, or Flammkuchen in German) is the Alsatian equivalent of the Pizza, though extremely different. Traditionally, it is made of a thin layer of dough, covered with crème fraîche (rich sour cream), cheese, onions, and bacon (lardons in French). It is baked very quickly in an extremely hot oven so that it gets crispy. Legend has it that the dish was a solution to the extra scraps of dough left over from the bakers. Other regional specialties include the Black Forest cake (with raspberry, cream and sponge) and quiche Lorraine.
Alsace is also famous for their Bretzels (pretzels in English). They are fresh baked and soft with generous amounts of salt. Sometimes you can find them with melted cheese on top accompanied by smoked salmon or ham.
Alsace is also famous for their Sauerkraut (or choucroute in French). This is fermented cabbage served hot with boiled potatoes and a variety of meats. Choucroute aux Poissons (with fish) is becoming more widespread.
Alsace is a traditional area of wine production and its wine is widely esteemed in France and outside it. In Christmas time try the cooked orange juice with honey and spices and also the spiced (or mulled) wine served hot in many of the creperies or bars.
Alsatian wine is very unique and similar to some German wines. A popular tour is to take the Routes des Vines and sample the wineries along Alsace. Two well known wines that comes from Alsace are Muscat (fairly sweet) and Gewürztraminer (very sweet, more so than wines of the same name produced in other regions).
In any of the creperies, they will serve a apple cider, slightly alcoholic. Doux is the sweet version and Brut is the dry version. This is not an Alsatian specialty, all of the ciders come from Brittany on the Northern Coast, but it seems all French people enjoy crepes and cider so authentic restaurants catering to these foods are widespread.
Eau de Vie is a very strong alcohol, similar to a vodka but produced from fruit, which gives it a distinct flavor. It was originally produced by the monks of the region. Look for the Eau de Vie de Mirabelle, which is a regional plum unique to Alsace.
You can use it as your starting point for travels in Alsace.