No two snowflakes are exactly alike, but their forms usually fall into several basic types. During snowfalls look closely at snow and you will see beautiful snow crystals made of ice. Many people think snowflakes are made from frozen raindrops, but this is simply not true. A snowflake forms when water vapor in the air condenses directly into solid ice. As more vapor condenses onto a nascent snow crystal, the crystal grows and develops. Amazing crystal structures appear during a simple act of water condensing into ice. The shape of snowflakes is formed by different air conditions during snowfalls. They are complex, symmetric and in varying designs. Snowflakes are the product of a rich synthesis of physics, mathematics, and chemistry. They are even fun to catch on your tongue :) Below you can see close ups of snowflakes, there's a lot more to see than you might think!
Also there are shapes that look totally different than usually imagined. Take a look at these beautiful ice crystals.
Pictures taken from SnowCrystals.com