Officially, wanderlust is defined as: 1) "a strong desire to travel" (Oxford English dictionary); 2) "strong longing for or impulse toward wandering" (Merriam-Webster dictionary); 3) "a strong desire for or impulse to wander or travel and explore the world" (Wikipedia, adapted from the Oxford dictionary).
Colloquially, it means that your list of places to go never gets shorter, no matter how many you cross off your list. It means that you love staring at a map or list of destinations at an airport and imagining the places you'll go. It means you love getting your passport stamped, even though standing in immigration and customs lines inevitably drive you mad.
But, you're told that wanderlust is not actually a good thing, that it takes your focus off of your work in the present, that it only distracts you and makes you wish for things that are not possible in the foreseeable future for whatever logical reason (money, being the primary limitation for most people, but also timing, career, family, etc). You're told to get your thoughts out of the clouds and back to wherever the here and now is, to stop romanticizing because it's just boredom and laziness that makes you think you want to travel the world and experience new things, when you really just want to escape reality and should actually sit down and think about how you're going to get your life together (whatever that means).
No. Just no. What's wrong with having some traveling dreams? Have wanderlust and be proud that you do!
Honestly, yes, you dream of gorgeous awe-inspiring places and photos, but more importantly, you are also genuinely curious about the rest of the big wide world out there that you don't inhabit. Wanderlust and traveling the world is never about the Instagram pictures, the Facebook album of photos, or anything remotely related to the Internet and age of technology. (Yes, we all love taking gorgeous photos, but seriously?) It's about immersion into a new country, a new culture, a new outlook. Whether your wanderlust takes you to Paris or Indonesia, to the top of a mountain or the bottom of the ocean, it's about gaining some perspective. You don't have to know what you're looking for, you just have to keep your eyes open. Because then, when you get back, you'll be refreshed and ready to jump back into your life at home. Or you'll realize that you need to change something back home - that's valid too.
You do not just say this because it justifies your wanderlust, but because there is some truth in J.R.R. Tolkien's now-famous, potentially over-used and clichéd quote from The Lord of the Rings that "Not all those who wander are lost" (1954). Life in the twenty-first century is increasingly global and international. Every country and culture has its different nuances, practices, societal quirks, and expectations. How are you supposed to know what to say or do if you never go outside your own little corner? So if you want to learn and make the best of an international world by going to a ton of different countries, then do it and travel the world.