- Mobile, tablet and desktop are the three popular breakpoints.
Ususally they are at 480, 768, and 992 px. - Breakpoints should not be fixed but should be custom depending on the type of site.
For example, whether your site has a 3 column design or a 1 column design. - More breakpoints means a more fluid and smoother experience.
But too many may make your site slower. - Experiment and see what works best for you site.
Try it across different browsers, devices and resolutions. - Do not target specific devices with your breakpoints as this is always changing.
Rather target what you feel will give the user the best experience.