I have no experience in biking and have never made any tour/route. I just like riding it. I love extreme and travelling in general and I am planning to start from small bicycle routes. I understand that it is a very general question, but what kind of bicycle would you recommend me to buy for it ? The tracks I am observing and choosing for future are mostly with surface: Paved, Unpaved, Gravel. So, I am more like a nature person, so I suppose I would choose mostly off road tracks. I was thinking generally about Touring Bikes. Maybe you would also give me some specifications I should pay attention. Any suggestions?
You also have cylcocross (CX) and gravel. They are going to more nimble than a touring bicycle and more design to handle unpaved. Many people use a CX with touring tires as a city, commuting, or all round bicycle.
Then you have a class called endurance. It is a versatile bike that is (typically) more roady than a CX. Look for one that will take 32mm (or even 35mm) tires. If it only goes to 28mm it is too roady for what you describe.
Also have bikes called adventure. They are designed for all round use and many are also designed for touring (rack mounts and a little longer). They are typically steel. If you want to tour with a load then go with this as the above more race inspired bikes and will typically not come with rack mounts. This style of bike is not going to be as nimble nr fast as the above race inspired bikes. Salsa Fargo is an example. If you have the coin something like a Moot Routt 45.
You could even go with a mountain bike with proper tires. You don't need dual suspension. You don't even need single suspension. You are not going to get very good road performance with the upright position. And drop bars let you spread out upper body fatigue.
Look used. At the end of race season you will often find some really good deals. You may be better off getting an inexpensive bike that fits in the space and get some miles under you before you settle on the perfect bike.
If you have the budget for 2 then maybe start with an endurance bike as with smaller tires it is a pretty legitimate road, trainer, and city bike.
No matter what get a bike that fits you. Consider retail just to get advice on a good style of bicycle and a good fit. Look for a shop that at least carries adventure type bikes.
I'm going to suggest you try a cheaper used bike before committing to anything expensive.
Your only real requirement is to make sure it takes larger-sized tyres. Off road benefits from wider tyres than on-road.
The top thing you need is a bike on which you feel comfortable.
In a year or so you can take your learnings, and decide what kind of bike will suit you best. Your riding conditions may change as you grow fitter.
Many keen cyclists own more than one bike. There's a running joke that all cyclists own N bikes each and they always want just one more ( ie N+1 )
One way of doing it would be to equip one bike so it only takes a short session to change it's set up for different purposes. I have a Scott Aspect 45, 26" wheel, mountain bike. I have mudguards, carriers and fat but smooth tyres. it came with suspension forks but, for loaded touring, I prefer rigid forks. It would take me less than 45 minutes to get the mudguards and carriers off and replace the sprung forks. I could then do some, unloaded, trail riding without the weight and bulk. It has a sloping top tube so it's a good stand over height, useful i stop/start traffic with 4 panniers, a rear top bag and a handlebar bag all loaded up with heavy gear.
PS... my n+ stands at 11 bikes and 3 trikes!