If you tweet "I am watching Mythbusters LOL" tap on that tweet, you will see no blue text meaning there is a link like an URL or similar.
If you tweet "This is the website that was just on Mythbusters www.lolz.com", tap on that tweet and you will see the web address itself is a hyperlink as it does in MS Word.
If you tweet "I am watching #Mythbusters LOL", tap on that tweet, you will see that the word Mythbusters and the preceding hash symbol have turned blue. The hash symbol preceding any combination of letters and numbers will turn those into a kind of hyperlink provided there are no spaces or other punctuation marks (@!"£$%^&*()\<>?:@~}{][#’;,./¬€).
This is called a hashtag. *cue angelic choir*
No, a hashtag.
If you press the hashtag from your (or any tweet containing one) it will then bring up, in chronological order starting with the most recent, all tweets containing that hashtag. That timeline of tweets will mostly be about the same subject. That is also why hashtags tend to be made of words which will define the search better than others.
Imagine if you wanted to do a Google search on ‘Mythbusters television show’ and typed in ‘television show’. That would bring back results on myriad programmes and not the one you wanted. If you typed in ‘Mythbusters television show’ then it would narrow down to relevant results. The same goes for hashtags. If you tweet "I am watching Mythbusters #television show LOL" or "I am watching Mythbusters television #show LOL" your tweets would not be as relevant to the programme as tweeting "I am watching #Mythbusters television show LOL".
Why should I tweet with a hashtag?
To best explain this, remember that Twitter is a social networking site. Though it is not face to face, users are interacting with each other socially through a network. You add a hashtag to your tweet if you want it to be seen by other users who are searching on that hashtag, so you connect with a wider network than just those whom you follow and follow you.
Are hashtags used only for television shows?
No. I have used television as an example but hashtags can be used for anything. If you hashtag something uncommon or spelt incorrectly, your tweet might be the only result in the timeline.
Does a hashtag have to be a single word?
No. It can be any words, any combination of letters and/or numbers up to 139 characters long. Although tweets are up to 140 characters long, if you want your whole tweet to be a hashtag, you need one character for the hash symbol itself.
Can my hashtag contain upper and lowercase letters?
Yes. It can be all lower case, all upper case or a combination of both. Personally I find if you are creating a hashtag out of two or more words, I capitalise the start of each word to make it easier to read each individual word, e.g. #ThisIsAHashtag
I see some television shows are displaying a hashtag on screen at the start of programmes. What’s that about?
Increasingly more and more live transmissions are getting audience feedback and input (such as questions for a guest) via Twitter. By displaying a hashtag on screen, it encourages viewers to use the same hashtag instead of a variety, all of which are perfectly relevant but would mean the show would have to keep refreshing the timeline on several hashtags, and might not capture all the hashtags in use. Of course this does not prevent viewers from ignoring the onscreen prompt but know that the people working on the show probably won’t see what you think about the programme.
There are some pre-recorded programmes which also display a hashtag. Again the people working on the show are probably gaining feedback but the tweets will not have any effect on the programme you are watching at that time.
Some programmes with hashtags displayed on screen
Question Time #BBCQT
Newsnight #Newsnight
Have I Got News For You #BBCHIGNFY (this is an example of the programme makers coming up with a hashtag for its vierwers to use without looking to see if one was already in use, which it was: #HIGNFY, and I noticed during the latest series, both hashtags being used as much as the other)
10 O’Clock Live #10OClockLive
Other unofficial programme hashtags
Top Gear #TopGear
Wonders of the Solar System & Wonders of the Universe #Wonders (this did not appear on screen during the broadcast of Wonders of the Solar System but Professor Brian Cox has tweeted himself that #Wonders is the hashtag for both shows)
Glee #Glee
Something For The Weekend #SFTW (this show asks its viewers to submit questions to the guests by tweeting an @reply to their account @SFTW, without seeming to realise they can get the same by using the unofficial hashtag)
The Big Bang Theory #TBBT
The IT Crowd #TheITCrowd
My Big Fat Gypsy Wedding #BigFatGypsyWedding / #BFGW
I recommend trial and error to find out what the common hashtag is for your chosen viewing.
Now I’m watching a live broadcast of Newsnight, what do I get out of putting the #Newsnight hashtag in my tweet?
Press the hashtag in your tweet to bring up the timeline of fellow users tweeting during the duration (or even after) of the show. You can then refresh this by dragging down the timeline the same way you refresh your general timeline. You then get to read what fellow viewers think of the show. It’s like dissecting a programme at the water cooler the next day but without having to wait then find a colleague who has seen the same programme.
Note: This was written using Mythbusters as an example as the person I wrote it for LOVES that programme.