If you're a content writer or an SEO, here's a thing you need to understand about how the human brain works. Research shows that the brain does not read every letter in a word. All it needs is the first and last letter to be in the correct places and it will automatically extrapolate the rest. Similarly, most readers will likely understand what a sentence means even if a couple of non-essential words are missing. Try to read this below:

Cna yuo raed tihs? I cdnuolt blveiee taht I cluod actullay uesdnatnrd waht I was rdanieg. The phaonmneal pweor of the hmuan mnid, aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it dseno't mtaetr in waht oerdr the ltteres in a wrod are, the olny iproamtnt tihng is taht the frsit and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it whotuit a pboerlm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Azanmig huh? yaeh and I awlyas tghuhot slpeling was ipmorantt!

As a content writer, coupled with the knowledge that humans have a short attention span, you can really craft out a nice article that is concise and keeps the audience interested just by removing a few non-essential words or even alphabets. So what does it mean for an SEO? Well  you can play with adding or removing keywords and even misspell a few words like the word "shoppng" or "freee" to cover a wider range of text indexing while your readers will not even notice it.