Although there are many tools and exchanges present out there,these (in the image) are the most popular & used ones
Among these the one exchange I would recommend to everyone is Binance.com
You can sign up for it here - https://www.binance.com/?ref=11630196
The reason I recommend Binance.com to everyone is because they have a lot of upcoming alt coins and if their is a new alt coin coming up there are strong chances that it would be released on binance.
A good tool for tracking your portfolio would be Coinmarket.com its the most widely used tool and is used by all market professionals.
NOTE- If you are a beginner or just entered into the market you can always refer to youtube.com
NOTE- Although these are the most popular in the world,BUT every country might have some other tools/exchanges.
Example - I am from India,I can not trade bitcoin directly by coinbase.com the most popular app/website in the USA.But I have local exchanges like koinex and coindelta to help me trade with it.
Thank you !
P.S - I am no professional blogger/writer PLEASE ignore my grammatical mistakes and vocabulary.
I keep my posts as simple as possible so that maximum people are gained by it.