Why there are flexible websites and other not?

[Tarek Scorpion]

hey guys i have a question since long time ago.

now when i go to Youtube or Facebook those sites are very flexible and fast so when i press on profile of someone in Facebook i can see his profile in less than a second , also Youtube when i click on a video i can see it fast and it move from a video to another in few seconds. but for example when i go to website like Vimeo or 500px as they are known websites they are not flexible and they are heavy so when i click on a photo on 500px it takes time to go to another photo etc also in vimeo if i want to see video and move to another it takes a while, what is the reason? can you let me understand?
thanks in advance

[JerryOfBorg]

The reason is called "bandwidth". Youtube and Facebook have multiple servers around the world and for lack of a better explanation have a huge number of wires coming out of their buildings. Imagine the largest number of racks of computer servers all in one place and then multiply them and put them all over the world. The other websites you mention are most likely smaller operations, which is OK as long as there are not a great number of users who wish to use them at the same time. Any of them can grow to be as large as Youtube in the future, but not right now.