A few weeks ago I purchased 15k usd worth of bitcoins (i've made a nice profit so far!). However I have read that you should never keep the coins on an exchange as this is unsafe. Right now I'm looking to take them off the exchange and keep them somewhere safer.

I'd like to know which are the best bitcoin wallets to store my cryptocurrency. What is the difference between the types of wallets available? I've heard about online and offline wallets. Apparently each of these have their own sub-categories.

How can I choose the safest type of bitcoin wallet? What is the difference between "cold" and "hot" storage? Any help is greatly appreciated.