Stars that neither rise nor set are called Circumpolar . They are always above the horizon. These stars never rise. They always remain below the horizon. Stars with high negative declinations will tend not to rise from northern hemisphere cities and may be circumpolar from southern hemisphere cities.
Stars have a fixed declination so their visibility remains the same for a given location.
However, the Sun's declination varies throughout the year. This was hinted earlier when the Sun's maximum altitude was shown to vary throughout the year. The table below shows the Sun's declination during the year. The reason for this is because the Earth moves around the Sun taking a year to do so. This path is called The Ecliptic and is shown below.