The strong beat in music requires the sound to be highlighted when playing. The weak beat, of course, means that the sound is not highlighted compared to the strong beat! (But it is not required to play in a low voice or softly.) We usually hear people say "having a plan and an eye." The plan here refers to the strong beat, and the eye refers to the weak beat. The distinction between strength and weakness is only relative. In the absence of special identification, the first sound of each measure is generally a strong beat, and the other sounds are sub-strong beats and weak beats.