Solid-state physics is the study of rigid matter, or solids, through methods such as solid-state chemistry, quantum mechanics, crystallography, electromagnetism, and metallurgy.
Because its particles are packed close together, a solid is rigid, doesn’t flow, and isn’t easily compressed. A solid is defined as a state of matter with a definite shape and volume. In contrast, liquids can change shapes, while gases can change both shape and volume.
Solids exhibit certain characteristics that distinguish them from liquids and gases. All solids have, for example, the ability to resist forces applied either perpendicular or parallel to a surface (i.e., normal or shear loads, respectively).
Without a break or opening; completely or continuously: The theater was booked solid for a month.