I've had 2 seizures before.
The first time was when I was at the doctor's office having a routine check-up. I was lying down on the doctor table and a nurse was poking in my ear with a Q-Tip. She must've poked too hard, because when I sat up I had a seizure. After sitting up, everything was slowly going black and then I must've passed out. Before I fully came to my senses, all I saw was blackness and I could hear myself grunting and feel my body shaking. When I fully came to my senses I was lying on the table again and had drool running down my mouth.
The second time I had a seizure happened about a year after the first. Once again I was at the doctor's office, but this time the seizure happened after I was getting tetanis and other shots. The same deal happened. Blacked out and woke up drooling. I wasn't so worried about it that time since it had happened before, but seizures still suck. The doc checked my blood because he believed I may have been anemic but it turned out negative.
Whatever. I haven't been to the doctor since. Bad things happen to me when I go there.
Before I fully came to my senses, all I saw was blackness and I could hear myself grunting and feel my body shaking. When I fully came to my senses I was lying on the table again and had drool running down my mouth.
Neither of them sound like seizures.
A seizure is when you lose the ability to control yourself, but you're still apparently conscious to other people. My uncle has epilepsy and I've seen him have a seizure before. It seems the brain cannot cope with the overload of senses and the person just freezes, shakes uncontrollably, or keels over.
What FatalT described sounds like a regular black out, often caused by a sudden drop in blood pressure in the head, because of sharp movement under certain conditions, or other things. I've blacked out on the station platform before. I was standing up, and I felt myself falling backwards, falling, falling, but couldn't do anything and when I woke up I was lying on my back with a bunch of Japanese folks crouching over me saying "are you ok?". My wife was with me at the time and called an ambulance. I felt lightly dizzy a few times in the hours after that, but that's probably because I whacked my head anyway.
Good times.