Note duration is the amount of time that a sound lasts for. Each unit of time is represented by a symbol.
The longest unit of time is the whole note (called the whole note because it lasts for a whole bar when using the simplest time signature, 4 beats per bar).One whole note equals the duration of two half notes.One half note equals the duration of two quarter notes.
Flags can be added to quarter notes to half their duration. A quarter note with one flag is called an eighth note. A quarter note with two flags is called a sixteenth note.
An augmentation dot increases the note duration by half.
Dotted quarter note = quarter note + eighth note (or 3 eighth notes).
Tenuto ties connect two symbols and combine their durations.For example two half notes tied together is the equivalent of writing one whole note. Ties are used to carry the note duration across bar lines. Below shows two whole notes tied together. Therefore the note should be allowed to sound for two whole bars.