A tie is a curved line joining two or more notes of the same pitch. Only the first note is articulated. The value of the extra note (or notes) is added to that of the first note. The initial note keeps ringing for the value of all the tied notes. Here are two examples:
Here are some examples demonstrating the use of ties both within a bar and across a bar line. Count carefully and if you are playing this, remember to hold the tied notes for their full value.
This example contains both staccato and slur marks.