Chai (or Masala Chai) is a term for spiced tea from India. The Chinese character for tea, 茶, is pronounced in Mandarin Chinese as "chá", and is the source of words for tea in many Eastern languages, hence "chai" in Central, South, and Southwest Asian languages as well as in Eastern and Central Europe and North and East Africa. "In the United States, many people refer to Indian tea as Chai tea, a redundancy (since chai means tea).  In India, prepared tea is sold in many varieties, the most famous being "masala chai" ([masālā cay]). Masala is the Hindi word for spice, and the spice mixture is sold as "chai masala." Chai is widely popular in India, and is also a relatively popular beverage in coffeehouses in other countries. (Source: Wikipedia)

In India, Chai can be purchased on the street by chai "wallahs," or vendors.  One can buy pre-packaged chai blends (tea bags or liquid), but, for the creative,  self-blending is a must.  In india, families traditionally have favorite recipes.  Among the basic spices used, one can fine cinnamon, cloves, pepper, cardamom,  and ginger.  The more venturous may consider vanilla, allspice, coriander,  licorice, fennel, or last, but not least, chocolate.

In the United States, Chai is used loosely as a term used for tea with spices, sweetening agents and milk. Chai lattes may be filled with cream or condensed milk, frothed in an espresso machine and topped with whipped cream!     Click for recipes and spice hints.

Espresso Machines often come side by side with a milk froth machine. Milk may be frothed by a kitchen gadget made just for that purpose as well. 
Froth can also be created by beating evaporated milk, sugar and vanilla.
Don't forget to crown the latte with chocolate shavings!