There are 129 seats in the Scottish Parliament at Holyrood. The most recent election to the Scottish Parliament took place on the 5th of May 2016. The SNP formed a minority government following the election. The current distribution of seats is:
The Presiding Officer Ken Macintosh (shown in black) was elected as a Labour MSP. By convention, the PO gives up their party status to impartially chair the Scottish Parliament. As such, the PO does not normally cast a vote.
Of the three MSPs listed as Independents two of them, Mark McDonald and Derek Mackay, were both elected for the SNP in 2016 but left the party following (unlinked) instances of harassment and inappropriate behaviour. The third is Andy Wightman, who left the Greens on the 18th of December 2020.
The Reform UK MSP is Michelle Ballantyne, who left the Conservatives on the 24th of November, initially sitting as an Independent. On the 11th of January 2021, she was announced as the Scottish leader for Reform UK, and changed her affiliation accordingly.
The current boundaries for constituencies (black lines) and regions (colours) of the Scottish Parliament are shown below. I’m still struggling to get a nice interactive version of this map, much to my annoyance! Shetland is enjoying a trip southwards in the graphic, for the sake of visual clarity in the Central Belt. More detailed constituency maps are available here.