Image source, GAVRIIL GRIGOROV/Pool/AFPBy Paul KirbyBBC News
Vladimir Putin has been in power since 2000, longer than any Kremlin leader since Soviet dictator Joseph Stalin.
As he prepares for a fifth term as president, aged 71, all semblance of opposition is gone and there is little to stop him staying on, if he wants, until 2036.
And yet, it was almost by accident that this little-known, former KGB man was hand-picked for the Kremlin. A case of being in the right place at the right time in predecessor Boris Yeltsin's inner circle.
Vladimir Putin was a street-fighting boy whose early years were spent in a communal flat, or kommunalka, in communist Leningrad.
Although he appeared to embrace liberal, democratic Russia, he later described the chaotic collapse of the Soviet Union as "the biggest geopolitical catastrophe of the [20th] Century".
Determined to prevent Ukraine from leaving Russia's orbit, he unleashed Europe's biggest war since World War Two, with a full-scale invasion on 24 February 2022.
He often justifies his actions with an outlandish perception of history and a keen resentment of Nato.
Before the invasion, and since, he falsely claimed that Ukraine was an artificial state populated by neo-Nazis. And he sought to stop Ukraine getting closer to Nato.
The Western leader who arguably knew him best was Germany's former chancellor Angela Merkel, who is once reputed to have described him as out of touch with reality and "in another world".
Image source, DENIS SINYAKOV/AFP
She repeatedly tried to negotiate with Vladimir Putin, but after he sent troops to invade Kyiv she came to the conclusion "he wants to destroy Europe".
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Vladimir Putin was born seven years after the end of World War Two – following the siege of Leningrad which killed his elder brother and which his parents barely survived.
He had a tough childhood that would affect the rest of his life.
In an interview in 2000, he remembered cornering a large rat on the staircase of his communal apartment block.
It had nowhere to run. Putin described the rat lashing out and throwing itself at him: "There, on the landing, I got a quick and lasting lesson in the meaning of the word cornered."
Image source, AFPImage caption, In 2000, a 10-year-old Japanese girl floored Mr Putin in Tokyo
The young Putin got into fights with local boys who were often bigger and stronger. Later, he would look back on that time and describe himself as a "hooligan". He took up judo, which he continued as a black belt during his presidency, and the Russian martial art of sambo, and stayed close to his childhood partners, Arkady and Boris Rotenberg.
In 2015, he reflected on his early experiences on the streets of what is now St Petersburg: "Fifty years ago the Leningrad street taught me a rule: if a fight is inevitable, you have to throw the first punch."
After studying at Leningrad State University, in 1975 he went straight into the Soviet intelligence service, the KGB. It was a natural step for a law graduate, and it suited him perfectly.
Image source, Other
It was also a dream job for a young man brought up on Soviet TV shows such as The Sword and the Shield, which recounted the derring-do of an undercover Russian spy in Nazi Germany.
"I was a pure and utterly successful product of Soviet patriotic education," he reflected.
By now, he spoke good German and he was posted to the East German city of Dresden in 1985 where he saw first-hand the collapse of a communist state in 1989.
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From the KGB headquarters across the road, he watched as crowds stormed the headquarters of the East German secret police, the Stasi. When a small group approached his building, he warned them off.
But when he called a Red Army tank unit for protection, he realised Russia was of no help: "We cannot do anything without orders from Moscow. And Moscow is silent."
The next year, he returned to a political system in free fall. He was given the rank of lieutenant-colonel, but never excelled at the KGB. One of his superiors, Nikolai Leonov, considered him a "mediocre agent".
To this day, he retains a small circle of KGB colleagues from Leningrad as his closest confidantes – long-standing allies such as Nikolai Patrushev, the secretary of Russia's Security Council.
It was not because of their "pretty eyes" he recruited them, his old judo coach Anatoly Rakhlin once recalled, "but because he trusts people who've proved themselves".
Those he trusts, he often enriches. He handed childhood friend Arkady Rotenberg a $3.5bn (£2.7bn) contract to build a bridge from Russia to occupied Crimea.
He is intensely private about his personal life, and divorced his wife Lyudmila in 2013 after 30 years of marriage. They had two daughters, widely named as Maria Vorontsova, an academic and businesswoman, and Katerina Tikhonova, head of a research foundation.
Image source, ReutersImage caption, Vladimir Putin's younger daughter, Katerina Tikhonova, is known to love acrobatic rock 'n' roll
From 1991, Vladimir Putin became deputy to the new mayor of Leningrad, Anatoly Sobchak, and a highly-valued adviser. When Sobchak was voted out, his deputy was headhunted to work in the presidential administration in Moscow.
These were the dying years of the Boris Yeltsin administration and Putin's rise was meteoric.
Image source, POOL/AFP
He spent a short time as head of the Federal Security Service, which replaced the KGB, and was then asked to report to the president as secretary of the Security Council.
On 9 August 1999, an ailing Yeltsin sacked his prime minister, replacing him with a little-known 46-year-old protege who would see through reforms ahead of presidential elections in 2000.
Yeltsin was by now in need of a successor.
"Putin had shown himself to be a liberal and a democrat, who wanted to continue market reforms," said Valentin Yumashev, who told Yeltsin he would make a "superb candidate".
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As Yeltsin's presidency faded away, Moscow was hit by a series of deadly but unexplained bombings. Vladimir Putin responded with a full-scale land offensive to recapture the mainly Muslim Russian republic of Chechnya from separatist rebels.
His popularity soared and on 31 December 1999 he was appointed acting president, winning his first presidential term three months later.
Thousands of civilians died in the Chechen campaign and, as he often does, Vladimir Putin used crude language to describe how he would wipe out the rebels "even in the toilet".
The capital Grozny was devastated; Russia's leader had his victory.
Image source, AFP
His first domestic challenge came in 2000, when the nuclear submarine Kursk sunk in an accident in the Barents Sea, with the loss of all 118 crew. President Putin remained on holiday and initially refused offers of international help. Many of the crew died waiting to be rescued.
TV viewers watched as grieving women screamed at their president.
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Four years later, Chechen rebels took 1,000 hostages, most of them children, at a school in Beslan, North Ossetia. When Russian special forces stormed the building, 330 people died. It later emerged that Russia had intelligence of a planned attack but had failed to act.
The first years of the Putin presidency were both bloody and turbulent, but the Russian economy was doing well, buoyed by high oil prices.
He won public support for taking on the billionaire oligarchs who had run rife in Russia in the 1990s. Summoning them to the Kremlin, he said they could keep their money as long as they kept out of politics and backed him.
He acted fast against those who didn't, such as Russia's then-wealthiest man Mikhail Khodorkovsky, who was arrested at gun point and jailed in Siberia.
Russia's president had something of a honeymoon with the West. He was one of the first foreign leaders to ring President George W Bush after the 9/11 al-Qaeda attacks on the US. He even helped the US launch its ensuing campaign in Afghanistan.
"I looked the man in the eye. I found him to be very straightforward and trustworthy," said President Bush.
But Vladimir Putin soon became disillusioned with the US and its allies. Relations with the UK soured when a former KGB agent and Kremlin critic Alexander Litvinenko was murdered in London using radioactive polonium-210. A UK inquiry found later that the Russian leader had "probably approved" the KGB attack.
On a visit to the Munich Security Conference in 2007, Putin made his feelings towards the US clear.
Image source, TIMM SCHAMBERGER/DDP/AFP
"One state, the United States, has overstepped its national borders in every way," he complained.
It was an icy reminder of the old Cold War and an expression of Russia's anger that the US was continuing to plan for a missile defence system in central Europe.
"The stones of the Berlin Wall have long been distributed as souvenirs… and now they are trying to impose new dividing lines and walls on us," said Putin.
It did not take him long to show he was prepared to use military power to undermine pro-Western leaders in former Soviet states.
In 2008, Russian forces routed the Georgian army and took over two of its breakaway regions – Abkhazia and South Ossetia. It was a very personal clash with Georgia's then pro-Nato President, Mikheil Saakashvili.
Vladimir Putin was by now prime minister, as the constitution barred him serving a third consecutive term as president, but it was clear he still held the levers of power.
Image source, ReutersImage caption, Vladimir Putin, seen here in 2015 with Dmitry Medvedev
Today that problem no longer exists. He steered through a law in 2021 that reset his limit to zero, which means he can head straight into a fifth term, and even a sixth.
Russia in 2024 is very different from the restive country in the run-up to the third Putin term.
In 2011, the biggest mass protests since the collapse of the Soviet Union erupted in Russia's major cities in response to widespread allegations of fraud in parliamentary elections.
Among the protest leaders was Boris Nemtsov, a liberal, former deputy prime minister in the 1990s. Another rising figure was anti-corruption blogger Alexei Navalny, who labelled Mr Putin's United Russia "the party of crooks and thieves".
Now genuine opposition has all but vanished.
Nemtsov was shot dead on a bridge, in view of the Kremlin, in 2011. Navalny survived a nerve agent poison attack in 2020, before he was thrown in jail in January 2021 and died three years later. His widow has accused Vladimir Putin of murder.
Putin has secured the support of the Orthodox Church and he has built a National Guard, or Rosgvardiya, that reports direct to him.
Acts of public defiance are few and far between, and newly-created offences targeting those who discredit the military and disseminate fake news are widely used to silence dissent.
Russia's media is largely pliant and controlled by the Kremlin, which has become consumed by an all-out war in Ukraine.
Image source, ALEXEY DRUZHININ/SPUTNIK/AFPImage caption, Yevgeny Prigozhin thrived for years under Vladimir Putin until he led an armed rebellion in 2023
Putin faced a short, armed rebellion in June 2023, when the formerly loyal mercenary leader Yevgeny Prigozhin sent his forces on the road to Moscow. But it was snuffed out and Prigozhin was later killed in a mysterious plane crash.
Some 40% of budget spending in 2024 will go on defence and security, as President Putin diverts much of the economy to the war.
Putin's war in Ukraine started, not in February 2022, but with the seizure of Ukraine's Crimean peninsula in 2014.
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The night that Ukraine's pro-Moscow leader fled violent protests in Kyiv and was effectively ousted, the Russian president said he held an all-night meeting and told his colleagues it was time to "bring Crimea back into Russia".
Pro-Russian agitators then seized swathes of Ukraine's Donbas region and war took hold in the east for eight years – until Putin decided he would invade from the north, south and east in a bid to overthrow Ukraine's elected government and seize Kyiv, with the invasion in 2022 .
He has repeatedly sought to justify the war. He writes long historical essays, gives speeches and lectures the few foreign visitors that come. But it is a distorted, selective history that brooks no dissent.
Civil rights group Memorial, which has devoted decades to remembering the victims of Soviet repression, has been banned.
Its veteran co-president Oleg Orlov was jailed for this description of the Putin era: "They wanted fascism, and they got it."
Source: bbc.com