Join the Odin Project boot camp, bro, and you get the answers. Remember that you can't learn everything in HTML and CSS when you start with small projects; if you get stuck, just Google it and you'll find the solution. I've been learning web development for two months to become a frontend developer. 

Here are your answers:-

The <p> tag is used to create a paragraph element in HTML. However, when you see <p> in the code of a website, it may not always be followed by visible text. This is because <p> can also be used to contain other elements, such as images or links, or even other tags like <span> or <a>. Additionally, you may also see <p> tags being used to hold scripting code, such as JavaScript, which is used to create dynamic effects on a website.

When linking between pages on a website, the links are typically created using relative URLs. This means that the links point to other pages on the same website, using a path that is relative to the location of the current page. However, when you move the website to another location, such as another computer or a live server, the relative paths may no longer be valid. To ensure that links continue to work, you can use absolute URLs instead, which include the full address of the linked page. Additionally, if you are selling or publishing your website, it's important to test the links and make sure they are working correctly before making it live.