Shakespeare's sonnet 73 is a formally typical example of a Shakespearean sonnet, despite being a poetically outstanding one. The rhyme scheme is abab cdcd efef gg, the usual four quatrains followed by a rhyming couplet, making fourteen lines in all. The meter is iambic pentameter.
The rhymes of this sonnet are fairly simple, single-syllable rhymes. The first rhyme, "behold" and "the cold" in lines one and three could potentially be read as a two-syllable feminine rhyme, but most readers would find that this throws an unnatural emphasis on the word "the," and avoid such a reading. The rhymes are all full rhymes in both Elizabethan and modern English, and their simplicity adds to the force of this powerful poem.
The iambic pentameter is smooth and regular, with no variation in the ten-syllable pattern. The only slight irregularity is the scansion of line eleven:
As the deathbed whereon it must expire...
If one scans this as a perfect iambic line, the word "deathbed" sounds unnatural, with the emphasis on the second syllable instead of the first. Shakespeare's intention, therefore, seems to be to disrupt the otherwise perfect iambic rhythm with the word "death." This means that the word "deathbed" should be read as a spondee, with two long syllables giving a marked emphasis to an important word.