My toddler started gnawing on raw carrots, celery sticks and cucumbers at one. She loves tomatoes too. When she first started, she would spit most of it out until one day, she just swallowed them and has never looked back since.
She takes her apples, pears, etc. the same way, with skin and all since 14 months. It's very convenient especially when we're out and about.
I was told by another mother to start them young so that they are used to all types of foods and not just the pureed stuff. I'm glad I followed her advice.