Your web browser sends a fair bit of data with each request. More data is created on the server about which pages you access and how you move around their website. Maybe you should reduce it by using Privacy Mode.
Every computer that accesses the internet has an address that is unique across the entire world. All this leaves a distinct footprint which is carefully logged for the purpose of advertising and user profiling. It can be analysed to great detail with specialist software.
text/html, application/xhtml+xml, application/xml;q=0.9, */*;q=0.8
SERVER SIDE FINGERPRINT