I was just wondering if it's possible to monitor HTTP requests sent & received to a WIFI network. If so, how is it done and how can I protect myself from it?
Some wifi hardware can be placed into monitor mode, and capture any traffic it sees. In this case it doesn't have to be associated with an access point (i.e. connected to any particular network). Wifi is just radio transmissions which can be intercepted with a suitably configured receiver.
Encryption is your friend. Make sure that your access point is configured to use a strong encryption scheme (WPA2 is the strongest scheme commonly available), and that the passphrase you use is long and strong. By 'strong', I mean that it should not contain any recognisable word or predictable sequence of characters, and should use a mix of letters, numbers and symbols.
If you don't control the access point -- in a coffee shop, for example -- you should ensure that any sensitive traffic you send or receive is encrypted 'end to end'. Make sure that you use HTTPS wherever it is available, and that any email client you use is configured to require an encrypted connection.
It is possible to monitor any and all requests sent/received through a WiFi network. There are many factors that contribute to protecting oneself to include using HTTPS protocols and implement WPA2.
Here are a plethora of threads related to WiFi and security of such: