The Raspbian Jessie Lite image is shipped as default with ssh disabled. This is a bit of a pain if you plan to use your Raspberry Pi headless straight out of the box.
Fortunately it is easy to get round this and enable ssh on the SD Card as you create the image.
Just create an empty file called ssh and copy it to the boot partition of the flash card.
To create an empty file in windows, use the following from the command prompt
copy NUL ssh