When transferring data (eg over the internet), speeds are typically expressed in bits per second. The unit should in general be written bit/s. The form bps is widely used in material for a general readership, where its similarity to kph (kilometres per hour) may be an aid to understanding. In more formal writing, bits/s is preferred, because it uses the correct unit symbol (bit) and is more in keeping with the standard way of writing units of measure: