What entails a tank
Well hello there people I am Muizz and I bring you a guide about tanks. Everyone thinks Taric and Nunu are tanks. Well yes and no, just because one has a high defense power doesn't mean they are a tank. A champion is only what someone builds them to be. Teemo isn't always going to be doing massive damage with his basic attacks teemo could build ap and do massive damage with mushrooms instead. Back to the main topic, a tank is someone who can withstand a hit and has abilities to come back from it. In theory Nunu and Taric can take a hit and can heal their health in dire situations to come back and win a fight but they still are a lethal threat. A tank doesn't mean a lot of health either or alot of armor it is a mixture of both. You cant buy tons of magic resist against an ap and think you are a tank. With magic pen you are nothing but if you combine it with health it makes a good threat. So to be a good tank you need to balance health and armor and know when to build magic resistance.
Items to build
Warmogs- I said not just health but I see alot of warmogs in champions that dont need it. For example you need warmogs on a nunu because he can only regen health if there is a minion nearby. Just because you can get it doesn't mean you should. Too many times do I see a taric getting warmogs and I see homer simpson facepalming himself at the same time.
Situational Items- AD Carries- Lets run a scenario quick, Phreak is on the opposing team with Master Yi and has a legendary kill streak and has aced your team several times. You being the tank try to figure out a way to counter him. You buy THORNMAIL(Possibly the best ad carry counter ever). Im not saying thornmail will kill Yi but it will help you tremendously. AP Carries- No explanation because if you don't understand you shouldn't be a tank. Banshee's Veil (Gives you a spell shield that is the only explanation you need.)
Tier God- The greatest tank of them all Volibear. (Rammus should be here too but i moved him to tier 2 because he is complicated.)
Tier 1- Rammus, Shen, Amumu, Nunu, Blitzcrank
Tier 2- Leona, Alistar, Singed, Maokai, Malphite, Galio, Taric
Tier 3- Dont play anything but these characters unless you know what your doing tank wise please