I prefer using a floor as I don't like being in a muddy tent during rain or snow.
A floor should be heavy vinyl for durability. Thin tarps available at Walmart will puncture if you have small rocks under your Walmart tarp floor when you walk on top of of them.
We have heavy 18 oz vinyl floors that are very durable. Competitor floors are normally 10-12 oz which are thinner and much less durable.
Never put a stove directly on top of a flammable floor for fire safety. Use fire mats under the stove or have a zippered stove area to remove.
Fold the sod cloth to the inside then place the floor on top of the sod cloth. In this manner, any water is forced under the floor. Also, bugs are forced under the floor reducing the number of insects entering your tent.
Always use a floor that does not have a stove cut out or zippered area because water and bugs can come in through openings in the floor.
Having a floor is recommended as it makes camping much more enjoyable. No dirt or water in the tent with reduced bug problems.
I am often asked if it is ok to use canvas as a tent floor. The quick answer is no.
A canvas tent floor will absorb water regardless if it is water and mildew treated. A canvas roof does not absorb water and leak because the roof is at an angle and rain runs down the roofline and side walls quickly. A canvas floor will have pools of water if you are in rain or snow conditions.
Additionally, a canvas floor will turn black and have mold on it. Not healthy.