Half and quarter lines are used in music notation to indicate the duration of notes. A half line (or a line with a slash through it) is used to divide a measure in two equal parts, while a quarter line (or a line with two slashes through it) is used to divide a measure into four equal parts.
For example, if a half line is drawn in the middle of a measure, it means that two half notes should be played to fill that measure. If a quarter line is drawn, that measure should be filled with four quarter notes.
These lines can also be used in conjunction with other note values, such as eighth or sixteenth notes, to indicate more complex rhythms.
It’s important to note that the use of half and quarter lines can vary depending on the time signature of the piece of music. In some cases, a single line may represent a different note value. It’s always important to carefully read the key and time signature of the music before playing to ensure that you’re interpreting the notation correctly.