Complex sentence: In its most popular form, it is thinly sliced--less than in thickness--and, typically (in North America), served on a bagel, often with cream cheese, onion, tomato, cucumber and capers.
Split into simpler sentences: In its most popular form, it is thinly sliced--less than in thicknes. In North America, it is typically served on a bagel, often with cream cheese, onion, tomato, cucumber and capers.