Understanding BPM and TPB
BPM (Beats per Minute) and TPB (Ticks Per Beat) are the two main forms of timing and speed control used throughout Buzz. These two items are used to adjust the general speed of your song as well as sync and time certain parameters.
Beats Per Minute
BPM is something that should be familiar to most musicians. BPM is the standard way to manage time in music. It literally refers to the amount of given beats per standard minute. What must be understood is that this is the amount of Beats Per Minute and not the amount of Rows per Minute. A row is actually equal to one tick. There for the number of rows in a minute is equal to the BPM times the TPB (i.e. Rows per minute = TPB * BPM).
Ticks Per Beat

What is a Tick you ask? The word 'Tick' is used to indicate the overall position in your song. As stated, a Tick is represented by a single row in a pattern. Simple as that. Every row within your pattern editor is equal to one Tick, and in sequence editor default one bar is equal to 16 Pattern rows, so to 16 Ticks. If you want to change this, read Understanding Bars in the Sequence Editor. The best way to explain the concept 'Ticks per Beat' is the probably the following example:

You compose a trance song, you standard assign 1 bassdrum hit every eight rows in the patterns of your bassdrum generator. In that case, if you want to have a commonly accepted tempo and you leave the BPM value between 120 and 150, you will have to set the TPB value at 8. Then you have your song orientated in 8 'ticks per beat' (the BPM multiplied by 8 will then give you the amount of rows that cover one minute of music).

Why does Buzz use ticks?
Ticks make for a nice common way to sync parameters and effects between each other, as well as the current song. For example it is sometimes useful to have delays be in "time" with the song. This means that each trailing repetition of the delay would need to hit exactly on a beat, with the rest of the song. While this would be very difficult to accomplish with units such as "milliseconds", it can be easily accomplished in Buzz by setting the delay unit parameter to ticks and then defining the number of ticks. Remember that each tick is equal to a row, so 4 ticks will delay every 4th row.