A tie is a curved line which connects two notes with the same position on the staff. The tie tells you to sing the first note only, and to hold it for the length of both notes. In the following example, the note G should be held for eight beats.
There are two common reasons for using ties. One is that this is the only way of indicating that a note is to be held across a bar line (see previous example) and the other is that a tie is a way of increasing the length of a note within a bar.
Here is an exercise to help you become more familiar with the use of ties. Once again, try clapping the rhythms while counting the beats out loud. Then sing the rhythms while tapping your foot on the beat. Make sure you don’t start tapping your foot on the written rhythms instead of evenly on each beat.