When it comes to plateaus most people are reactive. They will do "x" program until it stops working and then try something new. That may or may not work, maybe the body just needed a new stimulus to continue growth. Growth in fitness is seldom a linear path, the body will adapt to what you're giving it and you will plateau. In the words of Rich Piana "Confuse the Body". In fact Westside Barbell changes implements every few weeks for the same reason. Ie; Front squat, Back squat, Safety Squat bar etc.
So, what is Periodization? Periodization is a fancy word for programing a long period of time with a specific goal ensuring you never plateau. It's either unknown or misunderstood by 90% of recreational lifters or strength athletes. I'll break it down quite simply without using terms like microcycle, macrocycle, mesocycle etc. It's unnecessary.
Let's say your goal is to build size. You'll do 6 weeks of hypertrophy, a deload/rest week, 6 weeks of hypertrophy training, a deload/rest week, 4 weeks of strength, rest, 6 weeks hypertrophy, rest, 4 week muscle definition training.
This puts you more than half way through the year, with continual progress. Most people also find it more enjoyable to mix up their training rather than doing the same thing for 12-16 weeks.
Need a picture? (I'm a visual learner too)
The top row is the months. The number in the top right of the boxes is weeks.
AA: Anatomical Adaptation, this is for beginners or someone coming from a break typically light weights to allow the body to adapt to larger training volumes gradually.
H: Hypertrophy training focused on building size refer to my article for more information.
M: Mixed you could sub in Strength or Definition training here for this example.
T: This is your rest/deload week I would do light mobility and speed work here.
The real beauty of this kind of programming is how adaptable it is for many different goals, if you wanted to focus strength you would change the blocks, it's not a set in stone thing. I'll do 8 weeks of Strength/ Rest/ 4 weeks Hypertrophy/ Rest and repeat. I may find an area where I'm lacking and add extra hypertrophy training to that muscle group to aid in my strength training.
If you didn't want to build size you could easily sub in Definition, Strength, and Anatomical Adaptation training.