Shakespeare wrote a particular form of sonnet using three cross-rhymed quatrains (ABAB CDCD EFEF) plus a rhymed couplet (GG). He used iambic pentameter (taDUM taDUM taDUM taDUM taDUM). He was not the first or only poet to employ this particular sonnet form, which was all the rage during the Elizabethan era, but because he wrote so many, and wrote them well, and (perhaps more importantly), because they have survived, the sonnets in the form he used are known as "Shakespearian sonnets."
You can still write them today. You don't need to use Elizabethan English in order to do it (no "hasts" and "doths" and whatnot), but it is a fine way to rock a rhyme. In fact, I've written several for my Jane project, along with some other sonnet forms.
But Will's excellent skills can't be denied. I posted his Sonnet 18 two days ago, in fact, and I've posted others before, as a quick click on the "Shakespeare" tag below will quickly pull up for you.
Today, here's his Sonnet 98, which seems seasonally appropriate to me:
From you have I been absent in the spring,
When proud-pied April dress'd in all his trim
Hath put a spirit of youth in every thing
That heavy Saturn laugh'd and leap'd with him.
Yet nor the lays of birds nor the sweet smell
Of different flowers in odour and in hue
Could make me any summer's story tell,
Or from their proud lap pluck them while they grew;
Nor did I wonder at the lily's white,
Nor praise the deep vermilion in the rose;
These were but sweet, but figures of delight,
Drawn after you, you pattern of all those.
Yet seem'd it winter still, and, you away,
As with your shadow I with these did play.
Let's break it down for a moment, shall we? In the first quatrain (4 lines), the poet says "It's April, and spring is busting out all over, and I've been away from you." In the next two quatrains, he says "Neither the birds nor flowers put me in mind of summer, and I haven't been swept up in wild admiration of them, because while they were pretty, they were to me just weak imitations of you." The third quatrain is a bit of a turn from the first and second in that it discusses how he was too occupied missing the absent beloved to celebrate the beauty of nature. And the final couplet brings it all home, and gives us the poet's bottom line: "Even though I can see spring around me, it's still winter for me because you are away."
How swoonily romantic is that? Oh so very, in my opinion. Would that we all had someone writing us love poems like this.