If two notes are joined together with a curved line they are said to be 'tied'. A tie tells you to hold the first note for the length or all tied notes combined. This particular method of notation is quite rare in drum kit transcriptions as, generally, a drum can't play long and short notes. It's just hit and that's that. The most common occurrence of a tie is when rolls are used.
Listed below are some examples of tied notes with a brief explanation of what the notation means.
Example 1
In this example the two crotchet notes (beats 2 and 3) are tied. This means you will play the note on beat 2 and hold it for the duration of both beats 2 and 3. So the first crotchet is held for 2 beats.
Example 2
In this example the quavers on the '+' after 1 and beat 2 are tied. Here you will play the first quaver and hold it until the semi quavers on the '+' after 2. So the quaver is held for 1 whole beat, but that 1 beat is split across beats 1 and 2.
Example 3
Here the first minim and the following crotchet are tied. You will play the first minim and hold it until the quavers on beat 4. This makes the first minim 3 beats long.
