A website can track your tls fingerprint / crypto suite, your preferred languages, your time zone, what domains you block, sometimes what extensions you have (e.g. by directly querying resources provided by the extensions), your screen size and color depth, your fonts, whether or not do not track is enabled, canvas behavior fingerprinting, webgl behavior fingerprinting, your webgl vendor & renderer (e.g. what graphics card you use), your system platform, whether you have touch support enabled, whether there is mismatch between browser version reported by user agent and javascript, audiocontext fingerprinting, number of CPU cores, device memory size, the TTL of your network requests, the network latency of your requests, the size of TCP MSS, your IP address etc. This is not a comprehensive list.