Lots of different people use screen readers to translate and process text and images on screens (mostly visually impaired and blind people but also dyslexic people. I use one as I have trouble reading long text on screens).
Emojis
Many of these screen readers can translate emojis, but some older ones cannot. There can also be issues with reading intent from emojis if they are not labelled (as intent can also be something us Autistics struggle with). The 
[eye roll emoji] can mean many things: not again, typical, can’t believe it, fed up etc. So sometimes a description in text makes for easier reading and understanding for everyone!
Alt text can be used within square brackets to describe what the emoji looks like or what its intent is. So for my most used emojis:
[shrug] [dunno]
[laughing] [crying laughing emoji] [lol]
[waving hand] [wave hello] [hey]
Most screen readers can read alt text and will give a description for emojis, so try to use these alt text given above sparingly.
Also, it is interesting to note that there is a unicode attached to emojis that is read by the screen reader but these vary from site to site. Reading an emoji on facebook will sound different than reading one on LinkedIn!
Whether you describe the emoji with alt text or not too many emojis make a post unreadable. Imagine every other sentence explaining a small picture. This is even worse when a word is replaced by an emoji. My advice is to use them sparingly and add alt text to them if you feel it helps.
Image descriptions
To keep things accessible people can use image descriptions (such as mine on the infographic above).
Websites often have their own automatic alt text but they vary in quality. There is usually a small sentence to describe pictures and they’re often not particularly descriptive!
You can be playful with your image description or more formal. Either way you want to catch the essence of rhe image as well as any text on there. Use the alt text areas on social media when using an image and also share this at the end of your post (its not always easy to access the alt text otherwise! Also sighted people might like to read it anyway). Tiffany Hammond, Fidgets and Fries, always does great image descriptions that are personal and funny (she often shares pictures of her family).
Hashtags
When tweeting, hashtags need to have a capital letter at the beginning of each new word otherwise it comes out as one garbled word. E.g #WelcomeToTheWeeekend not #welcometotheweeekend.
Following these three simple rules can allow people to access information and engage in social media the same as every body else.
My intention is not to shame people who forget or have issues doing this, I want to make a community where people can help and ask for help.
Alt text and image descriptions can be simple and quick to do – I fully appreciate it won’t be for some: so ask for help from someone who is sighted / can read screens. This can just be a message on the post saying ‘Can someone help with ID please?’ There are some wonderful people out there who are willing to help.
When people continuously share images – and words with a coloured background – with no alt text or image descriptions, they are consistently telling blind, dyslexic and other people who use screen readers that we are not welcome on their page.
Please bare with me whilst I sort the accessibility of my page, I am totally new to website design but this is of upmost importance for me to learn.