Which Exchange can we use?

One of the recurring difficulties of Cryptocurrencies is the need to use multiple exchanges. How do we choose them and what are the differences between them? Let's be clear here!
Some exchanges allow the use of fiat currency (EUR, USD, GBP, etc.) with a limited choice of Cryptocurrencies, while others offer a wide range of Cryptocurrencies, but only after achieving a good level of longevity on the Market. . On the other hand, others offer only new Cryptocurrencies and of dubious reputation.
By organizing the dozens of available exchanges, we can divide them into three different types.
Currently there are:
- Peer-to-peer exchanges (among participants)
- Fiat exchanges
-Centralized exchanges
-Decentralized exchanges

Types of Exchange

Peer-to-peer exchanges: That’s an exchange between parties, i.e. it permits users to buy and sell cryptographic currencies with Fiat coins or goods in a given country. The first of this type is Localbitcoin, but many have locally appeared and there are high expectations for the Cryptocurrency10 platform that makes it possible for one to buy or sell Bitcoin, Ethereum and tether on the site. In addition to the possibility of making changes with movable and immovable (real estate) property, i.e. the purchase and sale of motorcycles, automobiles, boats, buildings, etc.

Fiat exchanges: This category includes exchanges called Coinbase, kraken or Gemini. These types of Exchanges permits the direct purchase of Cryptocurrencies with a fiduciary currency (EUR, USD, GBP,...), are among the most used. 
However, the problem with the use of this exchange lies in the fact that generally the choice of Cryptocurrencies to buy is quite limited. In fact, when they accept fiduciary currencies, these exchanges are much more subject to Government-imposed regulations against money laundering, customers’ recognition and identification.
They are also very slow to introduce new Cryptocurrencies, as they are sure of the reliability of the projects at the origin of the new Cryptocurrency, in order to provide products complying with the laws in force.
Investors looking for stable projects with a high risk and high yields also try an exchange such as Coinbase to buy Ethereum or Bitcoin, then convert them and eventually invest them in other altcoins and in a different exchange.

Centralized exchanges: This category includes exchanges such as Binance, Kucoin, Bittrex (although the latter also introduce the possibility of using US dollars).
These offers the possibility to exchange only Cryptocurrencies. To buy a certain altcoin, you have to use another Cryptocurrency such as Ethereum or Bitcoin, then convert it into the altcoin you want to buy.
Centralized exchanges are much less restrictive in terms of regulations because they do not accept direct use of fiduciary currencies. In addition, they offer the possibility to buy/sell only Cryptocurrencies that have achieved a certain degree of reliability on the market.

Decentralized exchanges: This category includes exchanges such as IDEX. These offer transactions only between Cryptocurrencies.
The peculiarity of this type of exchange lies in the excellent level of security because client’s personal information or purses on a centralized server are not backed up (as is the case with Fiat and centralized exchanges). In this way, a hacker will not be able to force the exchange server and therefore will not be able to steal data. This aspect should not be underestimated, because history has taught us that centralized exchanges have also been pirated.
It should be noted that decentralized exchanges are the quietest in terms of regulation and are generally ideal for the addition of new Cryptocurrencies. This can have a double aspect, as they allow investors to participate in recently launched and promising projects, while making them vulnerable to fraudulent projects that a centralized exchange would analyze in depth before admitting them for trading purposes.
A decentralized exchange is a great choice to an investor who has already done many market research before investing in a project. 

Instant exchanges: We will also add a fifth category of exchange, namely those that allow instant exchange of trust currency (with credit/debit cards) and the sending of the purchased Cryptocurrency to a personal wallet or to the user in a centralized or decentralized exchange. The most famous of this type is probably Changelly (it allows the purchase of at least fifty altcoins), but there are also others around the world. 
This way, you can also buy altcoins via a fiduciary currency, which you could not get through traditional centralized exchanges, and have them in your wallet within few minutes.
Finally, we can say that in order to be able to evolve effectively in the world of Cryptocurrencies, the four types of exchanges may be necessary: The reverse process can be exchanged in fiduciary currencies.