system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Does it rain over all the Oceans and Seas? Are any areas over an Ocean or a Sea classified as deserts?

Well I was watching some documentary and they mentioned ancient dried up seas. This got me wondering why they dried up, the obvious answer was the geology changed. But then I thought to myself, so why didn't a giant lake form here instead and I realised that since the geology had changed, there had been so little rainfall that the water all evaporated. 

Which means that a area over this Sea would not have gotten rain, making it a Desert, right?

Does that question even make sense? I am a bit high..
gpt
There are definitely bodies of water which get rained on more or less depending on where they are. The amount of precipitation which falls in the arctic is very small compared to that which falls in a tropical region. Areas of ocean which are downwind from deserts also get very little direct precipitation.

Oceans and seas which can accept ocean water can maintain their water levels because the water will slosh around to roughly even things out. If a body of water gets cut off from oceans, then the area which it can draw water from becomes a lot smaller and this sea is now going to be much more affected by local weather than the larger oceans. All surface water bodies evaporate and most seep into groundwater as well and many lose water to creatures (particularly humans in recent timse), but if the water isn't being replenished fast enough, then the water level will drop and eventually disappear, but many water bodies surrounded by land are able to find a balance point for a long time where their levels stay within a particular range across the seasons.