I'm not familiar enough with cuisine's technical jargon (unless it's French), so I'll direct you to this Wikipedia article
and beg for your absolution.
This dish is incredibly easy to prepare (10 minutes usually, down to 5 if you're an expert), but you have to be very picky about the quality of the ingredients and the order you use them. Do it right, and the result will always be FA-BU-LOUS.
The basic ingredients are lightly toasted bread, garlic, fresh tomatoes, olive oil and salt ("fleur de sel" is better if available).
Then, use your imagination and create your own variants. It's often served with some charcuterie (typically raw serrano ham or botifarra), or grilled vegetables like eggplants or sweet peppers, but you can also try cheese, guacamole, or whatever comes to your mind. Try it basic and simple (without additional ingredients) first.